Can't change Organization in Teams

Hi,

I've just been added to an external organization as a guest to their TEAMS Organization/Channel to work on a project. However, I cannot switch between organizations in my Teams.

When I open the teams from a link that was sent to me once they've added me, it opens TEAMS in their organization and I have option to switch to my organization with no problem... However, when I switch to my organization (or if I run Teams after restart etc), I do not see that second organization as an option so cant switch to it.... The only way is to close the TEAMS and open it by clicking on the link received from them.

What could be the issue here pls?