Do you use the same account in Outlook and Teams when you start a meeting?
It is the Teams app that does not handle multi-accounts / multi-tenants well at this point. In general, you should be signed into Teams desktop and Outlook desktop with the same account to avoid issues.
When you click the meeting link and sign into Teams, you will need to sign in with the associated account or organization that the invitation sent. If not, Teams will use your sign-in account or
organizational credentials to access meetings that are not invited. Because it was not identified, it was trapped in the lobby.
Using InPrivate / Incognito browser sessions is an alternative if having issues with the app. For more details about the policy settings in Teams, you could refer to this link's table.
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