Hi there,
had to cope with the same issue. When I opened the system settings I saw my POD HD 500x displayed as "Line 6 audio- MIDI devices". When I clicked on that line, the settings were empty. Especially the information that no driver was installed made me curious. So I downloaded the newest MAC-M1-driver from the Line6 website. After installing that, everything was fine. Good luck to you all! Hopefully this can fix your problems too...