[GAMEPLAY] Ezreal ult goes through Ekko without damaging him (random)

On Ezreal, if you ult Ekko, there is apparently a chance it does 0 damage even though you hit him perfectly. This happened again later, but he took that damage 2 seconds later (screen was running at high fps and low ms as seen in the video)(no video of second time). (The black bar above Ekko's health bar is to not show the player's name because I don't know him, therefor I can't ask his permission to show his name)

1. Ezreal ults
2. Ekko gets hit
3. Ekko doesn't take any damage (or it takes around 2 seconds to apply the damage in which he could kill you/an ally even if the ult damage would have killed him)

We tested this afterwards in a custom 1v1, and it happens randomly around 2 out of 19 ults (might be less, but this was the average while testing). (no video of the testing). No specific build, no specific actions, but completely random.

Edit after watching video several times again: It seems to only damage the first target hit (minion in front of ekko) and nothing else (ekko and the minion behind ekko/next to turret)