I have a glTF file at: https://github.com/sjhalayka/vulkan_shadow_mapping/blob/main/fractal.gltf​

When I view it using an online viewer (https://gltf-viewer.donmccurdy.com/)|, it looks fine:

However, when I load it using the sample code (https://github.com/SaschaWillems/Vulkan/tree/master/examples/shadowmappingomni), it ends up all messed up:

Any guesses as to why the model gets mangled?

The ray traced shadows demo is also broken. So, it leads me to believe that the glTF lib is busted?

This works: https://github.com/CesiumGS/obj2gltf

view with 3D Viewer, no problem

I'm still not sure why the mesh is so messed up in some apps. I ended up converting it from STL to glTF using Blender. Works just fine.