toshtest.3dm (1.6 MB)
Rhino 6 (vanilla) latest service release.
When I edge fillet the hole (red) 0.1 rolling ball, the shaded and render modes look wrong. Geometry looks OK in wire-frame.
Actually, filleting that edge produces bad objects, to solve this, you can Explode
your object, select the bad objects by SelBadObjects
command and then untrim
and trim
again to fix the problem: