When using bitmaps to mask projectors in Zinc on OSX – bitmaps created on a Mac don’t load into the Zinc application – Zinc grays them out so making it impossible to export a masked projector.

Solution
Save a 24 bit .bmp file from Photoshop
Transfer the file to Windows
Open it.
Save it.
Transfer the bitmap back onto the Mac
Zinc should now pick it up okay in Finder.