GLB/GLTF export not working?

Howdy - 
Off the bat, I'm not professional at 3D, but know enough to build some rudimentary things in blender. That being said I'm trying to export a sign from blender with 2 textures. They're showing up in GLTF viewer perfectly, but in Aero they're not registering at all. 

Any tips / tricks to exporting from blender -> GLB/GLTF for Aero?

I'm cruising the forums, but have yet to find an answer.

GLTF Viewer