Apple Classroom Update Unsuccessful

We used Apple Classroom with great success last year, using the same templates we did the sync for this year. If we have bad formatting, data incorrect, it will show us what the issue was. But once we get past that, we hit this problem where is just fails, doesn't do anything and won't give specifics.

Anyone know how to fix? I have even tried with a single student, single class, single teacher etc and still same unknown error.

[Edited by Moderator]