The Mk XII set pieces are only available if you get a rare drop in elite mode. The shield I have is the Mk XII Omega Force. Here are the screenshots I promised. I don't generally fly a Sovereign but I thought it was better for showing off the graphics than my little MVAM, although on the MVAM it makes some really neat looking dark patterns across the ship. Maybe I'll post screenies of that, too, in a bit. Anyway, on the Sovvy it looks a little more like the MACO shots posted earlier than I originally thought.
I already reported it yesterday, its clearly a bug, a friend of mine with the jem hadar ship had the same shield (MACO) and had the neat effect, while I didnt. And i tried enabling/disabling the visuals.
Must say though, it looks awesome on the jem hadar ^^