Every time I start wow on my mac the display is about 25% raised from the bottom of my screen when it loads the character select screen.
Easy fix is open the menu > options > graphics > monitor, then just select the other option (it has “primary” and “built-in retina primary” as options, which as far as i can tell are the exact same thing written 2 ways)
So, it’s annoying having to do this every time, but once I do it everything works fine.
Is there a simple fix?
This was happening to me as well. I honestly don’t know what fixed it but it’s not happening to me anymore. I just kept playing with the settings tbh.
Monitor: Built in Retina display (Primary)
Display Mode: Fullscreen (Windowed)
Resolution: 3024 x 1964
Render: 100%
Ui Scale 65%
VSync: Enabled
Notch: Shift UI Down
LL Mode: Disabled
AA: None
lucky you 
Not sure if this is related however occasionally I will get screen assets (like buttons or flight power bar) moved automatically out of the areas I have edited them to.
They dont reset back to their original location but are off kilter. This is random but usually after zoning into a new area or starting off for the day.
My work around is to go into Edit Mode, change my default to the standard UI then switch back - this fixes it and generally I dont have any other issues until the next gaming session.