Bugged Heimerdinger boss fight in Hextech Mayhem [PC]

I started playing Hextech Mayhem today, only to realize that I cannot beat the Heimerdinger boss fight due to a game-breaking bug. His turrets are supposed to shoot on beat, and you avoid them by hitting the notes on time. Here instead, his turrets seems to shoot sporadically, and multiple times, making you take damage you’re not supposed to.