They're attuned IOs I've been playing with. I've had them convert into the 4 other sets as well but going by that issue of EW being the only sub 20 set, it must be rolling to the set and then locking itself out from further rolls despite being a 10-50 set which would include the other sets withing most of that level range. Kinda makes all the other sniper IOs a potential pitfall for converting if it ends up wasting the IO category by falling into the EW set.