Hmm, I’ve had this error before - where it lost the category - and this is definitely different.
It just says “you cannot edit a poll after 5 minutes” (or very similar), and the category is still there and correct.
In my case, I was simply editing the “Next Week:” part to link to the following week. So from saying “Chapter 10 - coming 28th November” to saying “Chapter 10”.
It’s the same thing I do every single week for every single book club. Don’t even go near the poll. I’m fresh out of book clubs, so I don’t know if it will affect any other threads for me.