Lux ult bug

Played a ranked game as lux and even tho we won and I had a good score but when against a veigar mid who was running flash/barrier..there where 2 times that I counted where when timing his barrier to activate at the same time my ult would hit him dead on. it would (instead of dealing damage to him or his barrier) negate the lux ult damage all together. Both teams saw this every time it happend and no one could say why it was doing that. I do not know if this is just a random bug as lux vs veigar or if it is a bug where activating barrier at the moment of damage completly negates it. multiple players in the game on both teams even said they had seen it happen other times with lux ult dealing no damage.