concrete5 Environment Information
# concrete5 Version
Core Version - 8.5.7
Version Installed - 8.5.7
Database Version - 20210623000000
# Database Information
Version: 10.4.22-MariaDB
SQL Mode: NO_ZERO_IN_DATE,NO_ZERO_DATE,NO_ENGINE_SUBSTITUTION
# concrete5 Packages
Block Designer (3.4.0), Block Designer Pro (3.1.0)
# concrete5 Overrides
blocks/rkg_hotnews_homepage/add.php, blocks/rkg_hotnews_homepage/auto.js, blocks/rkg_hotnews_homepage/composer.php, blocks/rkg_hotnews_homepage/config.json, blocks/rkg_hotnews_homepage/controller.php, blocks/rkg_hotnews_homepage/css_form/bootstrap-datetimepicker-composer.css, blocks/rkg_hotnews_homepage/css_form/bootstrap-datetimepicker.min.css, blocks/rkg_hotnews_homepage/css_form/bootstrap.fonts.css, blocks/rkg_hotnews_homepage/css_form/repeatable-ft.form.css, blocks/rkg_hotnews_homepage/css_form, blocks/rkg_hotnews_homepage/db.xml, blocks/rkg_hotnews_homepage/edit.php, blocks/rkg_hotnews_homepage/fonts/glyphicons-halflings-regular.eot, blocks/rkg_hotnews_homepage/fonts/glyphicons-halflings-regular.svg, blocks/rkg_hotnews_homepage/fonts/glyphicons-halflings-regular.ttf, blocks/rkg_hotnews_homepage/fonts/glyphicons-halflings-regular.woff, blocks/rkg_hotnews_homepage/fonts, blocks/rkg_hotnews_homepage/form.php, blocks/rkg_hotnews_homepage/icon.png, blocks/rkg_hotnews_homepage/js_form/bootstrap-datetimepicker.min.js, blocks/rkg_hotnews_homepage/js_form/bootstrap.min.js, blocks/rkg_hotnews_homepage/js_form/handlebars-helpers.js, blocks/rkg_hotnews_homepage/js_form/handlebars-v4.0.4.js, blocks/rkg_hotnews_homepage/js_form/moment.js, blocks/rkg_hotnews_homepage/js_form, blocks/rkg_hotnews_homepage/view.php, blocks/rkg_hotnews_homepage, blocks/rkg_spacer/add.php, blocks/rkg_spacer/composer.php, blocks/rkg_spacer/config.json, blocks/rkg_spacer/controller.php, blocks/rkg_spacer/db.xml, blocks/rkg_spacer/edit.php, blocks/rkg_spacer/form.php, blocks/rkg_spacer/icon.png, blocks/rkg_spacer/view.php, blocks/rkg_spacer, blocks/rkg_special_teaser/add.php, blocks/rkg_special_teaser/composer.php, blocks/rkg_special_teaser/config.json, blocks/rkg_special_teaser/controller.php, blocks/rkg_special_teaser/db.xml, blocks/rkg_special_teaser/edit.php, blocks/rkg_special_teaser/form.php, blocks/rkg_special_teaser/icon.png, blocks/rkg_special_teaser/libraries/parsedown/LICENSE.txt, blocks/rkg_special_teaser/libraries/parsedown/Parsedown.php, blocks/rkg_special_teaser/libraries/parsedown, blocks/rkg_special_teaser/libraries, blocks/rkg_special_teaser/view.php, blocks/rkg_special_teaser, blocks/rkg_stage_content/add.php, blocks/rkg_stage_content/composer.php, blocks/rkg_stage_content/config.json, blocks/rkg_stage_content/controller.php, blocks/rkg_stage_content/db.xml, blocks/rkg_stage_content/edit.php, blocks/rkg_stage_content/form.php, blocks/rkg_stage_content/icon.png, blocks/rkg_stage_content/libraries/parsedown/LICENSE.txt, blocks/rkg_stage_content/libraries/parsedown/Parsedown.php, blocks/rkg_stage_content/libraries/parsedown, blocks/rkg_stage_content/libraries, blocks/rkg_stage_content/view.php, blocks/rkg_stage_content, blocks/rkg_stage_homepage/add.php, blocks/rkg_stage_homepage/auto.js, blocks/rkg_stage_homepage/composer.php, blocks/rkg_stage_homepage/config.json, blocks/rkg_stage_homepage/controller.php, blocks/rkg_stage_homepage/css_form/repeatable-ft.form.css, blocks/rkg_stage_homepage/css_form, blocks/rkg_stage_homepage/db.xml, blocks/rkg_stage_homepage/edit.php, blocks/rkg_stage_homepage/form.php, blocks/rkg_stage_homepage/icon.png, blocks/rkg_stage_homepage/js_form/handlebars-helpers.js, blocks/rkg_stage_homepage/js_form/handlebars-v4.0.4.js, blocks/rkg_stage_homepage/js_form, blocks/rkg_stage_homepage/libraries/parsedown/LICENSE.txt, blocks/rkg_stage_homepage/libraries/parsedown/Parsedown.php, blocks/rkg_stage_homepage/libraries/parsedown, blocks/rkg_stage_homepage/libraries, blocks/rkg_stage_homepage/view.php, blocks/rkg_stage_homepage, blocks/rkg_teaser_carousel/add.php, blocks/rkg_teaser_carousel/auto.js, blocks/rkg_teaser_carousel/composer.php, blocks/rkg_teaser_carousel/config.json, blocks/rkg_teaser_carousel/controller.php, blocks/rkg_teaser_carousel/css_form/repeatable-ft.form.css, blocks/rkg_teaser_carousel/css_form, blocks/rkg_teaser_carousel/db.xml, blocks/rkg_teaser_carousel/edit.php, blocks/rkg_teaser_carousel/form.php, blocks/rkg_teaser_carousel/icon.png, blocks/rkg_teaser_carousel/js_form/handlebars-helpers.js, blocks/rkg_teaser_carousel/js_form/handlebars-v4.0.4.js, blocks/rkg_teaser_carousel/js_form, blocks/rkg_teaser_carousel/libraries/parsedown/LICENSE.txt, blocks/rkg_teaser_carousel/libraries/parsedown/Parsedown.php, blocks/rkg_teaser_carousel/libraries/parsedown, blocks/rkg_teaser_carousel/libraries, blocks/rkg_teaser_carousel/view.php, blocks/rkg_teaser_carousel, blocks/rkg_teaser_xl/add.php, blocks/rkg_teaser_xl/composer.php, blocks/rkg_teaser_xl/config.json, blocks/rkg_teaser_xl/controller.php, blocks/rkg_teaser_xl/db.xml, blocks/rkg_teaser_xl/edit.php, blocks/rkg_teaser_xl/form.php, blocks/rkg_teaser_xl/icon.png, blocks/rkg_teaser_xl/libraries/parsedown/LICENSE.txt, blocks/rkg_teaser_xl/libraries/parsedown/Parsedown.php, blocks/rkg_teaser_xl/libraries/parsedown, blocks/rkg_teaser_xl/libraries, blocks/rkg_teaser_xl/view.php, blocks/rkg_teaser_xl, themes/rkg/content.php, themes/rkg/css/owl.carousel.min.css, themes/rkg/css/owl.theme.default.min.css, themes/rkg/css/styles.css, themes/rkg/css/styles.css.map, themes/rkg/css, themes/rkg/description.txt, themes/rkg/fonts/fira-sans-v10-latin-500.woff, themes/rkg/fonts/fira-sans-v10-latin-500.woff2, themes/rkg/fonts/fira-sans-v10-latin-500italic.woff, themes/rkg/fonts/fira-sans-v10-latin-500italic.woff2, themes/rkg/fonts/fira-sans-v10-latin-700.woff, themes/rkg/fonts/fira-sans-v10-latin-700.woff2, themes/rkg/fonts/fira-sans-v10-latin-700italic.woff, themes/rkg/fonts/fira-sans-v10-latin-700italic.woff2, themes/rkg/fonts/fira-sans-v10-latin-800.woff, themes/rkg/fonts/fira-sans-v10-latin-800.woff2, themes/rkg/fonts/fira-sans-v10-latin-800italic.woff, themes/rkg/fonts/fira-sans-v10-latin-800italic.woff2, themes/rkg/fonts/fira-sans-v10-latin-italic.woff, themes/rkg/fonts/fira-sans-v10-latin-italic.woff2, themes/rkg/fonts/fira-sans-v10-latin-regular.woff, themes/rkg/fonts/fira-sans-v10-latin-regular.woff2, themes/rkg/fonts/pt-serif-v11-latin-700italic.woff, themes/rkg/fonts/pt-serif-v11-latin-700italic.woff2, themes/rkg/fonts/pt-serif-v11-latin-italic.woff, themes/rkg/fonts/pt-serif-v11-latin-italic.woff2, themes/rkg/fonts/rkg-icons.svg, themes/rkg/fonts/rkg-icons.ttf, themes/rkg/fonts/rkg-icons.woff, themes/rkg/fonts, themes/rkg/full.php, themes/rkg/homepage.php, themes/rkg/js/jquery-3.5.1.min.js, themes/rkg/js/owl.carousel.min.js, themes/rkg/js/plugins/animation.gsap.min.js, themes/rkg/js/plugins/animation.velocity.min.js, themes/rkg/js/plugins/debug.addIndicators.min.js, themes/rkg/js/plugins/jquery.ScrollMagic.min.js, themes/rkg/js/plugins, themes/rkg/js/rkg.js, themes/rkg/js/ScrollMagic.min.js, themes/rkg/js, themes/rkg/media/close-a.svg, themes/rkg/media/news-01.jpg, themes/rkg/media/news-02.jpg, themes/rkg/media/news-03.jpg, themes/rkg/media/news-stage-content-desktop.jpg, themes/rkg/media/news-stage-content-mobile.jpg, themes/rkg/media/news-stage-content-tablet.jpg, themes/rkg/media/rkg-logo-footer.svg, themes/rkg/media/rkg-logo-mobile.svg, themes/rkg/media/rkg-logo.svg, themes/rkg/media/rkg-wappen.svg, themes/rkg/media/stage-schwung-desktop.png, themes/rkg/media/stage-slider-01-desktop.jpg, themes/rkg/media/stage-slider-01-mobile.jpg, themes/rkg/media/stage-slider-01-tablet.jpg, themes/rkg/media/teaser-gruppierungen.jpg, themes/rkg/media/teaser-tanzabteilungen.jpg, themes/rkg/media/teaser-termine.jpg, themes/rkg/media/teaser-xl-desktop.jpg, themes/rkg/media/teaser-xl-mobile.jpg, themes/rkg/media/teaser-xl-tablet.jpg, themes/rkg/media/ticket.svg, themes/rkg/media, themes/rkg/scss/bootstrap-grid.css, themes/rkg/scss/bootstrap-grid.css.map, themes/rkg/scss/bootstrap-grid.scss, themes/rkg/scss/bootstrap-reboot.css, themes/rkg/scss/bootstrap-reboot.css.map, themes/rkg/scss/bootstrap-reboot.scss, themes/rkg/scss/bootstrap-utilities.css, themes/rkg/scss/bootstrap-utilities.css.map, themes/rkg/scss/bootstrap-utilities.scss, themes/rkg/scss/bootstrap.css, themes/rkg/scss/bootstrap.css.map, themes/rkg/scss/bootstrap.scss, themes/rkg/scss/forms/_floating-labels.scss, themes/rkg/scss/forms/_form-check.scss, themes/rkg/scss/forms/_form-control.scss, themes/rkg/scss/forms/_form-range.scss, themes/rkg/scss/forms/_form-select.scss, themes/rkg/scss/forms/_form-text.scss, themes/rkg/scss/forms/_input-group.scss, themes/rkg/scss/forms/_labels.scss, themes/rkg/scss/forms/_validation.scss, themes/rkg/scss/forms, themes/rkg/scss/helpers/_clearfix.scss, themes/rkg/scss/helpers/_colored-links.scss, themes/rkg/scss/helpers/_position.scss, themes/rkg/scss/helpers/_ratio.scss, themes/rkg/scss/helpers/_stacks.scss, themes/rkg/scss/helpers/_stretched-link.scss, themes/rkg/scss/helpers/_text-truncation.scss, themes/rkg/scss/helpers/_visually-hidden.scss, themes/rkg/scss/helpers/_vr.scss, themes/rkg/scss/helpers, themes/rkg/scss/mixins/_alert.scss, themes/rkg/scss/mixins/_backdrop.scss, themes/rkg/scss/mixins/_border-radius.scss, themes/rkg/scss/mixins/_box-shadow.scss, themes/rkg/scss/mixins/_breakpoints.scss, themes/rkg/scss/mixins/_buttons.scss, themes/rkg/scss/mixins/_caret.scss, themes/rkg/scss/mixins/_clearfix.scss, themes/rkg/scss/mixins/_color-scheme.scss, themes/rkg/scss/mixins/_container.scss, themes/rkg/scss/mixins/_deprecate.scss, themes/rkg/scss/mixins/_forms.scss, themes/rkg/scss/mixins/_gradients.scss, themes/rkg/scss/mixins/_grid.scss, themes/rkg/scss/mixins/_image.scss, themes/rkg/scss/mixins/_list-group.scss, themes/rkg/scss/mixins/_lists.scss, themes/rkg/scss/mixins/_pagination.scss, themes/rkg/scss/mixins/_reset-text.scss, themes/rkg/scss/mixins/_resize.scss, themes/rkg/scss/mixins/_table-variants.scss, themes/rkg/scss/mixins/_text-truncate.scss, themes/rkg/scss/mixins/_transition.scss, themes/rkg/scss/mixins/_utilities.scss, themes/rkg/scss/mixins/_visually-hidden.scss, themes/rkg/scss/mixins, themes/rkg/scss/utilities/_api.scss, themes/rkg/scss/utilities, themes/rkg/scss/vendor/_rfs.scss, themes/rkg/scss/vendor, themes/rkg/scss/_accordion.scss, themes/rkg/scss/_alert.scss, themes/rkg/scss/_badge.scss, themes/rkg/scss/_breadcrumb.scss, themes/rkg/scss/_button-group.scss, themes/rkg/scss/_buttons.scss, themes/rkg/scss/_card.scss, themes/rkg/scss/_carousel.scss, themes/rkg/scss/_close.scss, themes/rkg/scss/_containers.scss, themes/rkg/scss/_dropdown.scss, themes/rkg/scss/_forms.scss, themes/rkg/scss/_functions.scss, themes/rkg/scss/_grid.scss, themes/rkg/scss/_helpers.scss, themes/rkg/scss/_images.scss, themes/rkg/scss/_list-group.scss, themes/rkg/scss/_mixins.scss, themes/rkg/scss/_modal.scss, themes/rkg/scss/_nav.scss, themes/rkg/scss/_navbar.scss, themes/rkg/scss/_offcanvas.scss, themes/rkg/scss/_pagination.scss, themes/rkg/scss/_placeholders.scss, themes/rkg/scss/_popover.scss, themes/rkg/scss/_progress.scss, themes/rkg/scss/_reboot.scss, themes/rkg/scss/_rkg-buttons.scss, themes/rkg/scss/_rkg-carousel.scss, themes/rkg/scss/_rkg-fonts.scss, themes/rkg/scss/_rkg-footer.scss, themes/rkg/scss/_rkg-header.scss, themes/rkg/scss/_rkg-homepage.scss, themes/rkg/scss/_rkg-icons.scss, themes/rkg/scss/_rkg-mixins.scss, themes/rkg/scss/_rkg-stage-content.scss, themes/rkg/scss/_rkg-stage.scss, themes/rkg/scss/_rkg-typo.scss, themes/rkg/scss/_root.scss, themes/rkg/scss/_spinners.scss, themes/rkg/scss/_tables.scss, themes/rkg/scss/_toasts.scss, themes/rkg/scss/_tooltip.scss, themes/rkg/scss/_transitions.scss, themes/rkg/scss/_type.scss, themes/rkg/scss/_utilities.scss, themes/rkg/scss/_variables.scss, themes/rkg/scss, themes/rkg/thumbnail.png, themes/rkg
# concrete5 Cache Settings
Block Cache - Off
Overrides Cache - Off
Full Page Caching - Off
Full Page Cache Lifetime - Every 6 hours (default setting).
# Server Software
Apache/2.4.52 (Win64) OpenSSL/1.1.1m PHP/7.4.27
# Server API
apache2handler
# PHP Version
7.4.27
# PHP Extensions
apache2handler, bcmath, bz2, calendar, Core, ctype, curl, date, dom, exif, fileinfo, filter, ftp, gd, gettext, hash, iconv, json, libxml, mbstring, mysqli, mysqlnd, openssl, pcre, PDO, pdo_mysql, pdo_sqlite, Phar, readline, Reflection, session, SimpleXML, SPL, standard, tokenizer, xml, xmlreader, xmlwriter, zip, zlib
# PHP Settings
max_execution_time - 120
log_errors_max_len - 1024
max_file_uploads - 20
max_input_nesting_level - 64
max_input_time - 60
max_input_vars - 1000
memory_limit - 512M
post_max_size - 40M
upload_max_filesize - 40M
mbstring.regex_retry_limit - 1000000
mbstring.regex_stack_limit - 100000
mysqli.max_links - Unlimited
mysqli.max_persistent - Unlimited
pcre.backtrack_limit - 1000000
pcre.recursion_limit - 100000
session.cache_limiter - <i>no value</i>
session.gc_maxlifetime - 7200
unserialize_max_depth - 4096
Not sure if this is specific to this Block though. Did you try this with a clean install of ConcreteCMS and see if you still have the same issue? Otherwise I'd love to have a video of the exact steps you do + the contents of the config.json file of the specific Block you are including in your composer form! This way I can try the same here, since it would be a guessing game to where the problem lays at this point.
Kind regards
Ramon