Named Virtual Classroom (MS Teams) is not saving successfully on activity

Summary:

We are just in the process of testing the MS Teams integration, but I can't get the named virtual classroom to save when I close the activity.

Content (please ensure you mask any confidential information):

Our IT department have set up the MS Teams integration using a dummy account. I've set myself up as an instructor and added the account. The user name doesn't match mine - I don't know if that matters? The system has accepted the account and I can add it to other instructors.

I can then find the classroom when I set up the activity. But the system is not saving the classroom details when I exit the activity.