I had a machine crash and had to re-build.
In the process I upgraded Monogame to 3.7
In one app I had a small mesh in wavefront obj format. It no longer runs.
The build tools handle it fine, but at run time you cannot load it. It throws an error about not finding material handlers.
I didn't have time to look at it, so I just converted the mesh to fbx and moved on, but someone should look at it.
I also had a pixel shader fail that previously worked. I had to change it to use a struct as an input so that all the semantics lined up. Not really a problem but interesting.