Yes. I am unlocked and had SS. Now I have stock recovery and can't flash anything else.
i would try flashing everything clean and starting over if you havent already, having had ss on and now a custom recovery may have caused issues, i dont know for sure. best thing to do is start over. here is an updated version of matts utility if you want to use that
edit, oops i read that wrong, you need a custom recovery like cwm or twrp, you cant flash roms in stock. the new recoveries are also found in the utility here and matts from the link.