09-14-2020 10:40 PM
09-14-2020 11:30 PMSolution
Try signing out and back in manually (top right corner), if on desktop app try clear the Teams cache. Go to %appdata%\Microsoft\Teams via Start and delete the content in the Teams folder.
If you know all permissions are OK it could be a backend issue as well (using Teams in an org?). But start with the above workaround.