Why am I stuck in a screen time passcode loop??

We use my husband's Apple ID to sign in to our 3 children's iPads and purchase and download all their apps etc. Screentime works just fine on 2 of the 3 iPads. One particular iPad is stuck. When I try to make any screen time changes it asks for the passcode. However, it says it's incorrect. I tried every possible passcode and nothing worked. On only 1 attempt left, I erased the iPad and restored it. I tried to set up screen time again. It let me go through the process of setting up a NEW screen time passcode and I used MY Apple ID to set that up (because it requires a different one from the one logged in, which is dumb). So I start trying to change settings and it asks for the passcode. That I JUST set up. It says it's incorrect. Again. Won't let me make any changes. So we contacted Apple Support via Twitter and we ended up erasing the iPad AGAIN and this time setting up manually like a new iPad, instead of restoring.

THE SAME THING HAPPENED!! I set up the new screen time passcode and it STILL said it was wrong again!! I can't set up screen time!!

I don't know what to do from here. It's stuck!!! HELP!!