Vel'Koz Ult bug on new SR

Played on the new SR just now in team builder. It only happened once, but yeah my ulti made the sound effect and just straight up stopped - the visual never even started. No I did not double tap the R button. No I did not issue a move command. The only thing hitting me was a blue melee minion. There was only one enemy, and it was a jayce who was running away - just at the edge of my ult range, so its not like he was anywhere near me or in melee form.