[GAMEPLAY] Jayce Q and Braum E Bug?

So, I was playing a game as Jayce and Braum would block my E(Acceleration Gate+Q(Shockblast) combo with his E(Unbreakable), and normally Braum would take absolutely no damage from the first projectile, being my E+Q Combo, and then take reduced damage from the rest for the duration of the ability, right? Well, in this case, wrong. He would completely block my combo's damage, and then also block the damage of the next incoming projectile, for example, there was a pantheon in the game as well, and he would throw is Q(Spear Shot) after my combo, and Braum would take absolutely no damage from both projectiles, and then the shield would "break" into its reduced damage mode.

I'm not sure if this is actually a bug or not, considering that Jayce's Shock Blast would normally explode on the first target it hits, instead of technically passing through the shield, but, the damage is still be completely negated by Braums Unbreakable, and isn't changing it into the reduced damage form of the ability.

TL;DR Jayce Q+E combo doesn't bust the first mode of completely negated damage on Braums E, allowing him to negate damage from another projectile as well.