[Posting this issue just so I can learn how to prevent this in the future with my own meshes].
I have a Glass Door mesh from the “ArchVizInteriorVol3” pack (SM_Backside_Door_Glass) that I pulled into my little “test room” project and the mesh is causing the Glass material to act like a mirror when Path Traced (no issues under Lumen). It’s the same regardless of my viewing angle and Sun position. Glass Material works fine with other meshes I’ve created and placed in this scene - so it’s DEFINITELY an issue with this specific mesh itself.
I’ve re-adjusted the U/V’s, Normals - no change. A checkerboard material applied looks perfectly fine. Any thoughts as to what is causing this when Path Traced?