Variable change trigger on layer not working

Hi folks,

I think there must be a simple explanation for this but I can't seem to find it. 

I am building a series of modules which have self-check questions sprinkled throughout. The questions allow unlimited attempts -- they must submit a correct response before continuing. 

The custom next button is on the master slide, and is shielded from view by a shape when the user first visits so they can't skip past it. I put a variable in place that is adjusted to "true" once a user has completed the question, so when they navigate back to the slide the submit button and the shape shielding the next button will both be hidden, and they can see their response and navigate back or forward. 

For the multiple choice/answer slides I put the adjust variable trigger on the "Correct" feedback layer, tied to the user clicking the "Continue" button. 

Unfortunately, it's not working. When you answer correctly and move on, and then navigate back to the slide, the Submit button and the shape shielding the Next button are still in place. 

However, for my T/F question slides, I used identical triggers EXCEPT that instead of putting the trigger changing the slide completion variable to True on the Complete layer tied to the Continue button, I put it on the base layer and tied it to the Submit button. And it works just fine! 

Variable changes normally work across layers/slides. Can anyone see what I'm doing wrong? I've attached a demo version of my file containing one multiple choice slide, one TF, and blank slides book-ending them for navigating back and forth.