Hi, first time I've ever seen this so not sure. Considering the troubleshooting already done I would probably open up a support ticket with Microsoft. But if you haven't already I would also reset the app by deleting all content here %appdata%\Microsoft\Teams and perhaps force an update of the Teams version https://gorovian.000webhostapp.com/?exam=t5/microsoft-teams/force-teams-desktop-client-update/m-p/2056566