Hello,
I’ve had the bug occur to me a good bit and here are the times I notice it happen most often:
The ‘eye beam’ shooting adds that spawn during the big boss fight that occurs just before you get to the end of time. Often using lunge on these adds will cause it, like 50% of the time, especially if they’re farther away.
The piles of bones that summon skeletons definitely cause it more often than other enemies as well. Happens like 50% of the time when used on them as well.
Lastly, if you have your mouse at the edge of your screen in the direction you’re going and spam the lunge key, you’ll end up casting it on something that you can barely see, or can’t even see yet, and this makes the bug occur almost every time.
edit: also there is a bug where if you take the node for 2 lunge charges, they both get used immediately when you use lunge.