I tried the Emacs forum but no one seems to know the answer so I am trying here. I built Emacs myself and it works fine that I know of and can open files in ~/Documents, etc but it can not open files in ~/Library/Mobile Documents. Emacs has Full disk access. I can do ^x-^f (find-file) as well as ns-open-file-using-panel (which uses GUI to open files) and ~/Library/Mobile Documents is not listed.
Emacs is 30.2. macOS is 26.
Emacs is 30.2. macOS is 26.