Bulwark insanely OP?

I don’t understand, the shield is just completely impenetrable? They just sit there taking it til you have to reload then pistol you to death or just steadily push you until you’re in melee range then you’re toast. Not even shooting head or feet seems to work? Unless you land a perfect grenade that class seems unkillable unless you surround it. What am I missing? Seems completely broken.