minor ekko bug

It happened in the gameplay, during the AI game. I was playing ekko, just fooling around, killing every AI with full items. The game was about to be over by destroying enemy nexus. I used w right next to nexus, and used zhonya's hourglass as the game was finished. The victory window popped up, my zhonya was over, and enemy Nunu came and killed me. I was very low health at the moment I used Zhonya's hourglass. Haven't tried to reproduce yet, but it seems like using zhonya and getting a shield from w skill might have to do with not becoming invincible after enemy nexus was blown up. I will try to reproduce later if I have a time.

Eddit: my item when it happened was 20-stacks of Mejai, Zhonya's Hourglass, Rabadon's Deathcap, Luden's Echo, Lich Bane, and Void Staff.