If you have access to multiple tenants as an external user via the one 365 account, there are some great edge cases. - I need to use the main menu to enter as

If you have access to multiple tenants as an external user via the one 365 account, there are some great edge cases. - I need to use the main menu to enter as a named external user in one tenant, to join and bypass the waiting gate to enter the call. Despite my main account being the same email, and indeed SSO! - While in that call, you receive notifications from chat messages in your main tenant chat inbox. - You can't use chat in your main tenant, as you're currently logged into a call as an external in another tenant (still using your main account), so you can see notifications for your messages, but can't reply to them on that device (!) This is before you consider the use-case of having multiple actual 365 accounts (which Microsoft seems to amazingly have failed to deliver on, despite the fact supporting it would likely increase their bottom line, by making it easier to add contractors into a tenant more easily). Strangely, this is supported far better on mobile, but not at all on PC (!) It seems they've built it on such a complex architecture of accounts, external users, guests, tenants etc, that they need to unwind this complexity to make it work - which tenants' policies should apply when on a call as an external user, but chatting in another tenant simultaneously?