New users are not being written to the DB. v 1.8.12

I have a dev server that is running in docker and we updated it to v 1.8.12 a little over a week ago. We are using SAML for authentication against our AD server. I just noticed that when a new user logs into the server their account is not visible in the user pane. It lets them log in and the account has default minimal user rights but when I look for them in the list they straight up are not there. I check the DB in the User table and the account is not written to the DB either.

I just tried with the same user credentials on our production server which is running 1.8.11 and that worked like a charm.

Besides the version the two systems are practically identical. Any ideas?