i'm assuming that only your flurry of bolts was missing?
i'm not sure if this is 100% correct, but from what i understand, it works like this:
raid bosses have 10% defense rating
basic attacks (flurry of bolts, hammershot, saber strike, etc.) have 90% accuracy, but other ranged/melee attacks actually have 100% like tech/force attacks (even though they're listed together in the character panel tooltip)
the reason you still need 10% accuracy for ranged attacks is to account for that 10% defense rating, but unless you have 120% ranged accuracy, flurry of bolts will always have a chance to miss.
was another attack missing aside from flurry of bolts?
I would agree here, but the bosses only have 8% defense chance. (And yes, every attack but your flurry of bolts will count your tech accuracy).
So, with 108% tech accuracy on my sniper the only attack that is dodged is rifle shot. It's the same on my smuggler but the offhand misses quite a bit. The offhand missing is fine though.