Maintenance for the week of March 16:
• PC/Mac: No maintenance – March 16
• ESO Store and Account System for maintenance – March 18, 6:00AM EDT (10:00 UTC) - 4:00PM EDT (20:00 UTC)
From this morning's PTS Patch Notes
The issue many Mac users have been experiencing is specifically called out for a fix:

This is the first time I've seen the "Mac game client" specifically named in the patch notes. I plan to test this out on PTS, and encourage other Mac users will do the same. I'm cautiously optimistic.