I wanted to upload a model to Sketchfab - which was quite high poly - so I decided to create a low poly version. For the low poly one I used the "Auto Smooth" setting in Blender to create sharp edges.
In the viewport the model has nice, sharp edges, but when I upload the .blend to SketchFab none of the edges are sharp.
I have encountered this issue before and exporting to .fbx fixed the edges. However, for some reason exporting this project to .fbx makes Blender crash.