When the workbench_moderation module is enabled and you have a webform revisions workflow configured you can't see the workflow state buttons and transition information (change form to publish or draft) on top of this if you then try to visit the Revisions tab on a webform the following error appears in dblog
InvalidArgumentException: $string ("") must be a string. in Drupal\Core\StringTranslation\TranslatableMarkup->__construct() (line 132 of /var/www/html/web/core/lib/Drupal/Core/StringTranslation/TranslatableMarkup.php).
no error appears if you simply create a revision but you aren't able to see the created revisions
To reproduce this error:
1. Install and enable the following modules:
2. Create a new workflow and configure it to use the Webform Revisions Config Entity Revisions types
3. Create an example webform with some fields (note the transition buttons are not visible) and then try to visit the Revisions tab and the error will appear