Below are known Drupal 8 core issues that are affecting the YAML Form module.
** [Issue #2808287: Importing YAML Form config file via the UI is throwing serialization error](https://www.drupal.org/node/2808287
Importing configuration file using Drush is working fine.
The YAML Form module provides drush commands to ‘tidy’ exported YAML and configuration files so they are easier to read and edit.
Any changes, improvements, and bug fixes for Drupal’s Form API may directly impact the YAML Form module.
Impacts previewing entity autocomplete elements.
Impacts displaying element description in a tooltip. jQuery UI’s tooltip’s UX is not great.
Drupal’s CKEditor link dialog replaces open dialog.
Makes it impossible to display the CKEditor in a dialog. Workaround: Use CKEditor’s link dialog.
Not sure this issue should be addressed by core.
#states API (Conditionals)
HTML markup (markup)
Managed file (managed_file)
Password confirm (password_confirm)
Text format (text_format)
Workaround is to manually build a static HTML link. See: \Drupal\yamlform\Plugin\YamlFormElement\Telephone::formatHtml
Workaround: Manually check form access. See: Drupal\yamlform\YamlFormEntityListBuilder
This blocks tokens from being inserted easily into the CodeMirror widget. Workaround: Disable ‘#click_insert’ functionality from the token dialog.
Config entity does NOT support Entity Validation API
Validation constraints are only applicable to content entities and fields.
In D8 all config entity validation is handled via \Drupal\Core\Form\FormInterface::validateForm
Workaround: Created the YamlFormEntityElementsValidator service.
Makes it impossible to open an action in a dialog.
Workaround: Add local action to a controller’s response.