Sketchfab color issue

When I tried loading my shark model to sketch fab, the color of the sharks eye does not appear as it does in blender. Either the Iris and eye ball colors flip or the entire eye becomes white, with only a slight line indicating where the Iris is.  I separated the Iris from the eyeball and changed its materials. Everything looks good in blender's render view...

Just wondering if anyone would have any ideas on how to fix that? Thanks in advance!