Two issues I encountered when trying to customise gear in the new system:
1. My Reveries Dawn Legs (hunter) from Season Of The Chosen would not allow any shaders– when highlighting shader options all are blank and this prevents an apply all in the transmog screen too.
2. The Gambit Prime Notorious/Illicit sets only have the green snake version of the helm, arms and legs available– although the icons for all colour sets are shown they only appear green (reaper).