Problem face in .sat export

[CADacombs]

The middle image shows how some corner fillets are split into multiple faces after STEP or IGES exporting the attached model (left image) then importing into Fusion or another CAD system.  When the same model is exported to .sat, the single face is retained, imports well back into Fusion, but cannot be read by other (non-ShapeManager only?) CAD systems, e.g., right image (per ShareCAD ).  Is this a case where the corner fillet is really a ShapeManager, not an ACIS object, and Fusion should convert it before exporting to .sat?

    

Thank you

[TrippyLighting]

I think that hypothesis is wrong. My hypothesis is that the other CAD systems simply can't read the ancient .sat version Fusion 360 exports. ZW3D can read this fine. I looked at the CV distribution as well (no screenshot)  just to make sure this was not just a display gimmik.