TLDR: Textures moved/stretched in mapping node not exporting with said transformations.
For the model I am trying to export, I have two image textures I am using. When I export as an FBX and view with windows 3d viewer all the image textures are missing or black. When I try to export to Sketchfab, the textures appear, but they don't have any of the transformations made in the mapping node. (squished, see image)
New to Blender.
enter image description here