It is strange.
The next things I would check would be some of the ui json files in the jsondb folder in userdata. Maybe there’s some error that’s crept into the session data in user.json or some of the autogenerated pages in uicomponents_ui_page.json.
If you don’t see anything obviously wrong with them you can compare them to versions in the backup folder from before the issue and see if anything has changed there. If you see something suspicious or definitely wrong, you can swap in the backup file or try to fix it yourself (after carefully reading the Editing the JSONDB, a last resort section in this post.)