Using Variables to Disable Next & Returning to a Slide

Hi, Lisa. I use this technique often, and the first thing I noticed from your attachments was that you were setting the "Next" button to "hidden" and the visited value to "false"when the timeline starts. Anyone is welcome to correct me if I'm wrong, of course, but it seems you are adding an unnecessary complication. You could simply set the initial value of the "visited" states to "false" and the state of the "next" button to "hidden" in the states panel so the "Set state" command is not at risk of conflicting with anything else happening when the timeline starts. Otherwise, it appears you may be at risk of cancelling the state changes. 

Short version. Try setting the default state of the next button to "hidden" and the default "visited" values to "false" to remove a layer of triggers.