Black Squares appearing on my FBX export

Hello, I saw a few posts about this in the past (but it’s not clear what the fix was). I am exporting an fbx, but when I open it in Quixel Mixer, these black squares appear:

Here’s the mesh in Blender, just a simple jar:

I’ve tried exporting it as an OBJ and get the same result. I radically altered the shape to, tried adjusting smoothness, but no difference, the black squares will sometimes appear in different places but will always be there, and in texturing they wont cover up.

I’m not using any add-ons, running on Mac OS Mojave 10.14, Blender 2.8.

I appreciate any wisdom regarding this issue anyone can offer, thank you!