Multiple Response checkbox won't change from Selected to a Disabled state

I have a multiple response question that has 4 answer options, and 2 answers correct (in other words, users must click both of the answers to get it correct). If the user selected a wrong answer, the Incorrect Feedback Layer appears. On the Incorrect Feedback Layers, I have triggers to change all check boxes to the Disabled state, where I've applied different text styles depending on right and wrong answers. I've noticed that when a user clicks 1 of the right answers, that correct answer does not change to the Disabled state--it remains in the Selected state. How do I force that state change away from "Selected"?