BUG Mercenary - Sometimes when moving it cancels attacking

I don't know how to explain this bug, but sometimes when I auto move while having my ammo equipped on mouse and keyboard (left click move) and I try to right click to cast my grenades, my character doesn't cast the grenades and just keeps auto moving.

It happens a lot and often, and it's not due to the lack of available grenades (i've checked every time if I was out of grenades, which was never the case)..

It also sometimes happens when I am trying to left click + shift to shoot with my crossbow..
It makes the character feel janky and clunky when it happens which sucks.. It feels like the character keeps "sliding" towards the point I pressed with the mouse, not being able to cast while doing so..

I do not know if it's because it's designed for controller and wasd or what, but I like playing with keyboard and mouse better, so I hope it's a fixable problem..
Probably could also be all that constantly being shoved around by mobs that are interfering, I don't know..

Oh, and my setup is:

Left click: Explosive shot + move
Right click: Explosive grenade