I have SW2010 S.P4.0 and Photoview 2010 S.P4.0.
I have created a simple cube part file in SW and added a standard default decal from the SW decal list.
When I render in Photoworks the decal is visible.
When I render in PhotoVIEW the decal is not shown.
I have tried this with various decals and some custom decals of my own, none are visible in photoview.