Not all elements are exporting with USD file (missing textures and Objects)

I’ve been trying to export a scene as USD for use in Nvidia Omniverse and every time I try to do so there are some elements of the scene that get left out. A few objects show with no texture, and some do not have their models at all, leaving behind. A shadow from the baked lighting.

This is what the scene looks like within Unity

Versus what the USD leaves out

Another example of how the scene should look in Unity

And how that looks as a USD