Value cannot be null. (Parameter 'key') error in my app...

[PatrickChoi]

Account ID : (PII Removed by Staff)

App name : TDC

1. Go to for example my brands data and regenerate schema for that data and the error appear.

2. I can make the error disappear by only reverting to my latest working app version..

This is keeping me up at night.

I see previous encounters with this bug on this post too...
Any admin might please help!
https://www.googlecloudcommunity.com/gc/AppSheet-Q-A/quot-Value-cannot-be-null-Parameter-name-key-qu...