If I try to add or remove an instructor, an online volunteer, or a campus volunteer, I get an error message. The user will actually get added or removed, though.
Probably related, the "Add students" tool available to instructors does not work. It results in a message saying the user does not exist.
The problem with add students tool for instructors is API-related, though I haven't worked thorugh all the details yet... So far, it looks like the issue with adding volunteers or instructors is, too...
Change 208101 had a related patch set uploaded (by AndyRussG):
Update API calls following core changes
The above Gerrit change fixes all the issues mentioned in this task. :) (Note: not yet deployed...)
Change 208161 had a related patch set uploaded (by AndyRussG):
Update API calls following core changes
Change 208162 had a related patch set uploaded (by AndyRussG):
Update API calls following core changes
The fix has been deployed to the cluster, so everything should be working smoothly again! As always, please give a shout if you find anything amiss...