You don't understand his problem.
Before pre-patch you could as a Shaman for example : Equip a piece of cloth and transmog this piece of cloth to another piece of cloth.
After pre-patch you can only transmog your "correct" armor type to your "correct" armor type, you can equip a leather item but you can't transmog it to another leather item because your Transmog tab can only see your "correct" armor type.
That's OP's problem.