In previous versions, I was able to export a model straight to a file using "Export mode: Model". Attempting to export as a model now gives a prompt for Upload Paste or Upload Gist. I have no desire to upload my model anywhere, only to have a file I can use locally.

CustomPlayerModels-1.18-0.4.3a.jar
Forge-40.1.52

Make sure the Skin Compatible checkbox is turned off.
Model files also have a limit of 30kB, after that you still need to use the Gist or Paste.

Issue was the texture file was too big then, or at least I assume that's why. It was a 256 x 256. Skin compatible was off.

I feel like the mod should give some feedback regarding this but maybe I missed it.