Scheduling Teams meeting stopped working, meetings do not show in Teams Calendar

Hello,
I have always scheduled successfully meetings in my Mac desktop Teams app via Teams Calendar ahead of my classes, assigning the meetings to a specific channel of each class. However, a few days ago that stopped working. Teams Calendar shows the meeting, but the color and spinning wheel indicate that Teams continues setting up the meeting. After a short time, the meeting disappears altogether. This behavior persists with Firefox and Chrome.

I have deleted all caches, de-installed Teams, reinstalled Teams, logged out of Office 365, etc. No solution so far.

Would appreciate your ideas and help very much!