Progress Meter Bug with Menu Use

I developed a progress meter for one of my courses and seem to run into an issue that I'm sure someone has solved :) 

The progress meter is on the slide master and has different states showing and increase in progress. I have created a number variable for "Progress" and set a list of triggers that change the state of the progress meter depending on the value of the Progress variable. 

On the content slides, I created triggers that add or subtract from the Progress variable as the end user clicks the previous/next buttons. 

This works perfectly...... until I use the menu to navigate back to the beginning. When I do so, no subtraction is done to the variable and the end user's meter only increases.

Should I program this variable differently? Or, is there a workaround that I can add?

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