Guys, I made a Youtube video about this issue. It's actually pretty easy to fix. Just requires some editing to the config file. I'm surprised this hasn't been covered in the forum or the FAQ of this website.
https://www.youtube.com/watch?v=OF-dfJEvYrY
First, and foremost you will have to change the line
dtoverlay=vc4-kms-v3d,cma-256 to
dtoverlay=vc4-fkms-v3d,cma-256
Adding the "f" in front of the kms. Then it should display on whatever screen you're using. I found this out the hard way. If that doesn't work, I've added a couple of optional things you can try.