Same with mine this morning. 1.16.4 java I do believe. ours is called district 12.. don't know if that helps.
I think i know what the issue is. I think there were half slabs under the the ones behind and i didn't have them in those ones. ...
THANK YOU.
This was fixed in paper https://github.com/PaperMC/Paper/issues/5994. Please update.