The new app/new accounts broke this. It will show “No access to libraries” for new accounts being created, even though they have them shared. Going to app.plex.tv shows the libraries correctly, but the new app and Android TV apps show an error or spin infinitely.
Doesn’t seem like this issue has been acknowledged officially yet (random workarounds like changing DNS or the device names have been suggested).
Inviting newly created users to libraries is broken if using the new app (which isn’t a choice for them by the looks). So I assume whatever new architecture is being used for new accounts isn’t working somewhere.
