best response confirmed by samjar87 (New Contributor)
@samjar87 - Hi Sam this worked for me. Bit of a faff but it did the trick. Hope it works for you. Mike

Unistall the Teams app;
Open your appointment in Outlook;
Click the "Join Teams meeting" link/button;
Install the Teams app that you are prompted to install;
After that Teams worked just fine.

It whirled for a little while and I have no idea what happened but it works now. I'm sure it will be a bug fix going forward for the big apple!