Tenant Account switch area not appear in my command bar after having accepted invitation

[pchetrit-accele]

Teams program opened (and connected to his own tenant account), when the user click on the Teams link in the invitation mail he received from another teams user (another tenant), he is having a web page asking to choose someting lige "launching teams web app  or downloading Teams App ... ?!!

And in his Teams app, the tenant account switch area never appears ...

And his Teams app can no more be re started (endless loop, displaying stealthily an office365 authentication screen popup ...)

[#2]

Ask the user to Sign out and Sign in again

[#3]

How signing out if the user can't no more open Teams ? And why that phenomen (what is the cause) ? How avoiding it ?

[#4]

You should see the Sign out option if you right-click on the Teams icon in the tray/taskbar. Apart from that, clear the Teams cache as detailed for example here: https://blog.valeconsulting.co.uk/2018/09/28/clear-the-microsoft-teams-client-cache/