Targeting reticle being placed automatically for some reason 50% of the time

About 50% of the time, when I cast spells that require me to place a targeting reticle, the spell just starts casting wherever my mouse is. But 50% of the time it works perfectly normal… the green circle comes up, I place it where I want it, and then it starts casting. I have Vile Taint bound to 3 on my keyboard, and I can stand somewhere out of combat, and just press 3 over and over, and watch the green circle sometimes come up, and sometimes the spell starts casting. It’s been happening for 2 days, and it is happening on all of my characters, not just my warlock.