I can't imagine what about MCP's quick casting could possibly conflict with this, unless it somehow breaks the function of GetSpellReadied. If that is the case, there isn't really anything I can do about it...you would just have to disable the hand-breaking aspect of this mod.
Ah, about this, I figured that it didn't have to do with quick casting, but it was because I had pressed the 0 hotkey, making hand to hand equipped. That, plus the button locking made the bug appear.
Also, I'm having a problem. Apparently hand breaking got bugged in some other way and even when I rest multiple days, my hands never heal and my weapon drawn button is never unlocked. Disabing the mod, loading, and activating it again didn't work (it was still locked when I loaded without the mod), so, is there a way to unlock the weapon draw function key via console?
I tried using the hotkeys to draw weapons or hand to hand, and even though that DOES make my character draw the weapon, it doesn't unlock the key.