[Gameplay] Health Bars don't change when any unit is attacked except when ultimates are used

So I just played a game of Mordekaiser, and halfway through the match after I ulted the enemy Kayn for a kill I noticed that no matter how much damage was done to anything (champs, minions, turrets, etc., both allied and enemy), their health bars didn't budge.

I tried restarting the game but the issue persisted, though I did notice that health bars did change whenever someone used their ultimate on someone. (Blitzcrank ulted my Vayne and I saw her hp bar and the minions' hp around them go down, I could briefly see my Nasus' hp bar going down for the short while we were in my ult, etc.)

(Also another thing though I'm not sure if it's relevant to this bug, but at the end of the game Vayne kept teleporting all over the place instead of moving, I checked my ms and everything was fine and all other players and the map could be interacted with normally except for Vayne's character behaving oddly, dunno what that was about either.)

Dunno how it happened and if I can even get footage of it, but if I do manage to get something I'll edit it into this post.

Anyone else run into this bug?