Polling doesn't work

When I add a poll to a post and submit, it throws a 500 error. I tried refreshing, but the same error gets thrown.

When I check the game, it turns out it did post, but without the poll attached.

I tested it out in one of my games, and had about the same result - except for me there was no error message, just blank page (https://gamersplane.com/forums/process/post) on Firefox. It posted the thread without the poll, too.