Manage Playtest Groups results in unexpected error

FYI - I just created a whole new Team through the Content Service, and then created a new Playtest group, and it mostly appears to be working. I had to go to the Creator Portal to get the join link.

In this new Team / Playtest group, I can see:
Creator Portal - can see the playtester!

Content Service - can see the group, but not the tester: