We use Sensitivity labels in our organization to classify and protect our data (co-auth enabled as well). What seems to happen is that if you have a PowerPoint presentation that is protected (excluding a one that you specify the permissions manually / Apply your own permissions) and you try to click the button on "Present in Teams" it doesn't work, your screen shows a message that states:
The participants on the other end see the following:
I couldn't find any documentation whether this is some sort of limitation so I am only guessing it is a bug?
EDIT: Just wanted to let everybody know that it is working now. We didn't change absolutely anything, wasn't working in the morning and in the afternoon it started working.