Viktor Q Shield Bug

Was just playing Ranked as Syndra and was bullying this Viktor in lane. I was 1-0 and hit level 6 first when I all-in'd him and my ult with at least 5 orbs did literally no damage to him after his proc'd his shield thus costing me my ult's cd, Ignite cd, and ofc the kill gold. This happened twice. Still won, but it's an annoying thing that can only be explained by it being a bug.

It seems this isn't just a problem when vs'ing Syndra: https://www.youtube.com/watch?v=nI6H-feU2xk