I've been a user on Notebook.ai for a long time, and some of my pages are old (2+ years). I haven't checked them all, but some of them have odd behavior.
Some of them show a description on my personal viewer, but when I go to edit, the text is nowhere to be found. I found this on universes/33907, /universes/34104, /universes/33907, but also /races/19489 (I had to re-write the field). Could this be because there was a data field that got renamed or moved during an update?
Some don't allow me to edit them, throwing a nonspecific error 500 (characters/85494/)
Earlier a page wouldn't even let me view it, but that was fixed (thanks andrew (Our Supreme Lord and Overseer)!)
I don't see a pattern, other than these are older pages. As a result, I'm not sure what other pages could be having issues except by trying to poke at them one at a time.