I do not know the cause, but When I used my super I got 3 shots with nighthawk equipped. I have way of the sharpshooter equipped. I have only had this happen once.
-
Same has happened to me twice in the last week. Used Celestial Nighthawk for Pit of Heresy boss encounter and suddenly had three shots in stead of one powerful one.
-
Did you just change the armor before using the Super? Or were you wearing the armor all the time? There have been issues with certain armor mods which were not working until you changed the armor piece again or you died. Might be a similar issue here.