EDIT. 4:08 It looks like this is a problem with CKEditor5 under Drupal 10.3. Anyone who has an issue that sounds similar to the title, check out https://www.drupal.org/project/drupal/issues/3458029 for more information.
I've come across a perplexing problem of relatively recent origin. Can't find anything on Drupal.org or any of the normal spots that helps out. I'm hoping someone here may have come across this and might have some ideas.
Recently updated the site to Drupal 10.3.1 as part of the regular update cycle. Also took the opportunity to upgrade PHP to 8.3.9 so we are ready and compliant for D11 whenever it comes along. I have no idea if this is relevant, but I'm including the details just in case.
We have several content types set up, some of which use a combination of Paragraphs and CKEditor 5. Since the update, we've discovered that when you open up a content node that contains some combination of Paragraphs and one or more CKEditor 5 boxes, any previous content is missing in Edit mode. The page seems to still display per normal, but you cannot edit or even see the content in Edit mode.
I saw one aborted discussion on Drupal.org where the person submitting the issue was asked if they had "Limit allowed HTML tags and correct faulty HTML" checked and if unchecking it resolved the issue. The OP never answered the question but as it happens I do not have this checked.
Any ideas? We have a very demanding stakeholder and she's already beginning to hyperventilate about this issue. Thanks in advance.