Teams: external channels - complete different behaviour between Windows/MAC and webapp/desktop app

Hi,

there are many posts on external channels not showing, but none seem to apply to what i see.

As soon as the old teams app is not available anymore i will loose access to some of my external channels:

So i have been given access to 7 different channels of an external origanisation.

This is what i am seeing:

Windows - old teams desktop app: All 7 channels are visible and I can access both "Posts" and "Files"

Windows - new teams desktop app: None are visible

Mac - new Teams desktop app: none are visible

Mac - old Teams desktop app does not work anymore

For the Web app of teams the behaviour is consistant between MAC and Windows (as expected):

Windows - new Teams Web app (in Edge browser): i can see 3 of 7 channels, i can only see posts and there is a bar on top telling me "the external organisation needs your permission to give you access to all features in the shared channel" there is a link "Review permissions", but if I click it nothing happens, so i cannot give my permission.

Windows - old Teams Web app (in Edge browser): i can see all 7 chhannels and have access to both Posts and Files

Mac - new Teams Web app (in Chrome): i can see 3 of 7 channels, i can only see posts and there is a bar on top telling me "the external organisation needs your permission to give you access to all features in the shared channel" there is a link "Review permissions", but if I click it nothing happens, so i cannot give my permission.

Macs - old Teams Web app (in Chrome): i can see all 7 channels and have access to both Posts and Files

Any help or hints is appreciated.

Raoul