About 20 minutes into the game, none of the health bars on minions or monsters started ticking down anymore.
The animations would go though, the damage numbers would appear, but the health bar would stay full.
The minions did die when their hp reached zero, but it wouldn't show any health value between full and zero.
This bug made it impossible to CS properly and secure dragon/baron since they were permanently at "full health."
This same bug occurred for dragon, all jungle camps, and the enemy nexus.
Note: sometimes if the minions survived long enough, their health bar would adjust to the correct value. Only happened once or twice, not consistent.
Additionally, inhibitors were "untargetable" and didn't show a health bar at all. You could still click and damage them, but the mouse would show the untargetable icon (red sword with a cross through it).
Finally, note the minimap.
We had false vision of the purple team's side of the map despite having nothing that could provide vision. The fog of war just wasn't there.
We couldn't see any units in those areas, but having no fog of war was a serious impairment to the game.
These bugs lasted until the end of the game, and as it turns out our Tristana had the exact same problems. (spoke with her at the endgame screen)