I had a complex model that I created in Blender 2.79, and imported (with some tweaking) successfully to Unity 2018 a few months ago. When I switched to Blender 2.8 and Unity 2018.2, I found big problems with my model.
Blender 2.8b tells me that all the normals are exactly what I expect – the blue shows all the normals are pointing outside, as they should.
But these 2 screenshots from Unity 2018.2.19f1 show the normals are all off.
I’m using Unity’s “import normals” option. I tried letting Unity recalculate them, but that didn’t solve the problem.
This is because the mesh is set to render transparent, not because of the normals. In reality the normals were OK on both versions but you got lucky with polygon winding order I think. Or simply used an opaque shader before.
Test it by using an opaque shader pass. If it’s the case then the problem will easily resolve even with transparency, by making sure the handle is a separate object or element.
It’s taking Blender about 6 minutes to export the file to fbx (just 20k vertices) and it’s taken 8 minutes for Unity to load it in. But yes, I see the “transparent” rendering mode, and now I see how to change the material.