You’ve got one of those monitors with those ridiculously small pixels…
There have been issues with those before, maybe you can find them on this forum if you search for it.
You can also experiment a bit with: … / Preferences / Preferences / Common / User Interface and then “icon scale”, “Canvas Scale” and the other settings in that part.
Try to switch to fallback graphics rendering. Should be in the preferences menu or reachable via some hotkey (F11 or F12). If this solves it then a graphics driver update would be an option to get opengl rendering working again.
Please try the accelerated modern toolset. If you are on a Retina display, then you will need to use the accelerated version otherwise you run into issues with the canvas being the wrong size.
KiCad has different ways for rendering the GUI built in and you can switch between them with F11] and [F12].
You can also find these in the menu of most KiCad sub programs in the main menu under Preferences
I sadly have no expirience with Mac. I edited your post title to make it clearer what is going on so hopefully somebody who knows something gets interested.
You can also make a bug report over on gitlab as what you see should not happen.
Same problem with OS 10.14.6 on Macbook Pro - 2014
Kicad 5.1.8
Footprint editor is black and shows nothing else.
Tried some of above and nothing helped.
I also couldn’t get the grid to display in Symbol editor, the orgin did display however. Played with some options and settings with no joy.
My system seems to be bypassing F11 and F12 - do they have menu items somewhere?
Edit: SOLVED!
Preferences Menu -> Legacy Toolset seems to have restored my graphics.
Background is now black and parts appeared.
I figured that also when I didn’t find the file. Searched for a config file with no luck - I’ll go on a hunt later but the problem seems to have resolved itself for now.
Once the legacy setting started working I switched it to “modern” and that worked too - maybe some kind of initialization problem?