Cannot consistently do heavy melee with mouse 4

[Kaxology]

It's kind of a small issue but I've been using mouse 4 to do heavy melee swings but it started working inconsistently since the new patch. I used to be able to consistently do heavy melee with mouse 4 with it very, very rarely ever registering a light melee, now it's sometimes a light melee and sometimes it registers a button hold. I've not changed my mouse and I've tested to make sure that my mouse 4 is working correctly, I don't really know why or how this happened but it seems to be a problem with the game itself. Pls fix and thank you.