Hi ATom&,
I'm Nik, an independent advisor here to assist you with this.
May I know if you join a class over a channel meeting or Instant meet now call by the teacher?
Could you please provide me with some more information to understand the scenario? Also, if you have a screenshot to visualize the situation that will be helpful.
Please blur any personal/sensitive information before sharing screenshot here.
Just in a side note, There are multiple ways to join a meeting, could you please double-check whether you are unable to find the join button in another medium such as email, MS Team mobile app etc. Please refer to this article: https://support.microsoft.com/en-us/office/join...
Regards
Nik