That's correct.
I'm logged in my company environment incl. Teams.
I received a Teams-Invitation from a partner company I work with.
following the link of the invitation I have to log in again, but this fails
If I click on my user account in Teams I see the list of companies: my own, and the new onw. But the new one from my partern with a waring signal "red triangle"
clicking on that company link to change to the partner I get the error massage that my admin has to activate Teams and informs me that I'm logged in with E-mail xy, which is my MS365 account.
For me it seems that in teh background there is an authentification issue. After we implemented MS365 we had serveral similar issues as we have used OneDrive before with the same E-Mail accounts and it seemed that MS has 2 different user directories for MS365 business and others