I’ve got the same issue from a long time (at least 0.20-q-GSI ). Perhaps due to a ‘no-account’ setting in main profile, wich result in a greyed ‘File shuttle’ button in Shelter’s setting menu.
In sheltered apps the ‘Share’ button allows to drop files in main profile’s app (Mail, Files, Message). ‘Add a file’ can pickup in main profile, too.
The file shuttle togle in Shelter settings is on but grey. I cannot flip it.
In the main Settings the accounts menu shows an /e/ account in personal settings. in Work are two accounts one from the Telegram app and one from Whatsapp. If I try to settup my /e/ account there (in work) it replies: Login failed!
please check your username and password,
The same account works in main! ?