F4c3m4n:
I had a problem like this before, and this is how I fixed it. Go to whatever static mesh that the NavMesh hits, or is on. Click on the Static Mesh, go to the Details Panel of that mesh, then UNcheck the little box, so that the particular Static Mesh won’t affect your navigation. I really hope this helps!
After that you will probably have to rebuild paths to fix it! Go up top in the UE4 Editor and click on Build, then click Build Paths, just in case you didn’t know. Good Luck!
Update, it worked but my nav for my VR pawn is a little wonky and not working correctly. It also won’t let me go to places on the map where the mesh is built.