Yesterday I noticed that some category pages I'd recently opened in the new UI wouldn't display any content but the introduction. When I opened it up again in athena, it was thankfully clear that nothing was deleted, but I noticed that the fields themselves were not in the position I'd moved them to. I've also had trouble with the css field not remembering classes I added. After I rearranged the fields the page worked again. For troubleshooting:
I do not know how to consistently reproduce the bug, it doesn't happen to all of my categories. One thing the categories have in common is that I have rearranged them at some point in the previous UI, and the bug only happens after opening the category edit in the new UI.