Inbox remains empty while others folders work OK


I am using 3.38 Flatpak release on Ubuntu Focal. My email provider is
Connecting to the account seems to work without problem, but my inbox remains empty. Other folders (like Drafts) seems to be synced correctly. Moreover on the left pane the new mail indicator seems to work (shows “13” in my case, see screenshot), but nothing shows in there…

Thanks for your help