I agree that this may be corruption caused by 20w21a. I updated my server from 20w20b to 20w21a, and they're not working. Tried to back-port a world generated in 20w20b, updated to 20w21a, then back but nope. They won't spawn in the monument loaded in 20w20b originally, even on 20w20b. Nor does it help to update to 20w22a. Was hoping back-porting then updating would be a viable workaround, but alas no. Damage was already done by 20w21a.
Dzetki
I agree that this may be corruption caused by 20w21a. I updated my server from 20w20b to 20w21a, and they're not working.
Tried to back-port a world generated in 20w20b, updated to 20w21a, then back but nope. They won't spawn in the monument loaded in 20w20b originally, even on 20w20b. Nor does it help to update to 20w22a.
Was hoping back-porting then updating would be a viable workaround, but alas no. Damage was already done by 20w21a.