NEXT button on Modern player not enabling - possible cause offered

I produced a series of 6 separate tutorials all using the Modern player with the PREV - NEXT buttons enabled below the canvas. Each object was published in an LMS with an EXIT button set as the completion trigger. Results showed that everyone was able to complete the tutorials with the exception of about three trainees who put in support tickets indicating that they were stuck on a frame (different frames - not the same frame) because the NEXT button would not enable even though they clicked on the requisite objects to change the state of the NEXT button from Disabled to Normal. (The NEXT button was set to be Disabled on timeline start, then changed to Normal upon clicking through certain objects to a Visited state).

I could not reproduce the error, and there were no indications that the problems were restricted to a specific browser. In seeking further details from the trainees, no one mentioned any behavior that would be unusual.

However, in producing an alternative version of these objects to quash this problem (hopefully), I discovered what is likely to be the cause of this problem.

If the trainee clicks on the required objects to complete the tasks for the frame and then exits the program (to return to it later on), the object will not remember the Visited states in the required objects. So when they return to the tutorial, the frame will not remember that the trainee already clicked on all the required objects into a Visited state to change the state of the NEXT button to Normal. No matter how many times they click on the already visited objects, it will not change the state of the NEXT button to Normal.

The solution is to set the frame's "When revisiting" state to "Reset to initial state" - not the default "Automatically Decide" (it won't decide). The trainee will have to click through the objects again, but the NEXT button state will change.