Base layer object appears on layer even if deselected in timeline

Weird! That's definitely "unexpected behavior." In other words, there seems to be a bug. It might be related to the triggers that change the ovals to the hover state when the corresponding hotspot is hovered, especially since they start in the Disabled state. Perhaps when the hover state goes away, that somehow shows the oval under the layer, even though it's supposed to be hidden? 

• You'd need to submit a case to the staff to determine if that really is the problem.

The good news is that you could solve the problem by simplifying the slide, as shown in the edited slide in the attached file.

• Don't use hotspots. Instead, show the appropriate layer when the user clicks an oval. That lets you take advantage of the built-in states. The ovals will automatically display the Hover state when the user mouses over them. And, when clicked, an oval will automatically change to Visited. (I gave the ovals a Visited stated instead of Selected. I think that makes more sense, since the state indicates the user has visited that layer.)  

Other things I did to the slide:

• Deleted triggers that changed variables.
• Added a trigger that disables NEXT when the timeline starts with conditions that check whether any oval does not equal Visited.
• Added a trigger that enables NEXT when all of the ovals are in the Visited state.