ofxAssimpLoader::getMesh with texture only draws correctly with ofDisableArbTex()

I thought that rendering a .obj model loaded by ofxAssimpLoader would be pretty simple, something like:

ofMesh mesh = loader.getMesh(0);
ofTexture tex = loader.getTextureForMesh(0);
tex.bind();
mesh.draw();
tex.unbind();

There's one more important step, ofMultMatrix(loader.getModelMatrix());, but even with this the texture map doesn't seem to work correctly. As far as I can tell, it has something to do with normalized vs unnormalized textures, but I don't have more details.

I made a full minimal example that works when ofDisableArbTex() is called, but uses the top left corner of the texture for the entire model when it is not called: https://gist.github.com/kylemcdonald/4ef96ffc1cc67c860fb35c38c71e6f51

With ofDisableArbTex():

Without ofDisableArbTex():

Start with the minimal example in the linked gist and reproduce the difference with and without ofDisableArbTex(). Trace the texture-coordinate handling around ofxAssimpLoader::getMesh and getTextureForMesh, then verify that the textured model maps correctly without requiring the workaround.