Hi Paul,
I can't open your .sldprt file, I have an older version of SolidWorks than yours. So I can't see what the original solid model looks like. But, I did import the .igs file into SprutCam and it looks complete to me, kind of a weird model but it appears to be all there... but again I don't know what the original SW solid model looks like
I have attached a screen cap of your .igs file as it looks in my SC. Does it look complete? If it does, maybe your graphics is the culprit, just a shot in the dark?
Gerry
PS
I always export out of SW an iges file of my solid model than import that into SC
Currently using SC7 Build 1.6 Rev. 64105