Having a course resume and keep the same variables

Our company has an onboarding checklist that I have turned into an online course so we can move away from the manual paper & scan option.

It features checkboxes and I created a variable to count the number of checks so once all boxes are ticked, and the variable reaches the correct number, a submit button appears so they can submit and we record their completion.

Everything is working fine except if someone checks a few items, leaves the course and the resumes later. Even with everything ticked the submit button won't appear - it seems like the variable calculation is incorrect.

The slide settings are set to Resume saved state when revisiting. If they just close the screen will that still save the state or should I add a close button to encourage them to use that is the close down?

If anyone had some suggestions on why this would not be working when resuming it would be appreciated.