Trying to create the slide so that the user must click on all 6 buttons before going to the next slide. Each button you click creates a new slide layer with the info, and has a "Close" button to go ...
It'd be easier to troubleshoot if you uploaded a .story file with the slide.
Best guess: Are you using a "Jump to this slide" trigger to close the layers? Yes, that does result in returning to the base. It also re-runs the trigger to "Set state of Next Button to Disabled when the timeline starts on this slide."
To close the layers, use a "Hide layer" trigger. That should keep the Next button enabled when the user closes the last layer.
By the way, your current trigger to disable the Next button will also re-run if the user revisits the slide. And then they'll be stuck, because the buttons are already Visited, so the program won't re-run the trigger to change Next to Normal.
To prevent that from happening, you need to add one or more conditions. For example, you use conditions that also check the state of the buttons.
Use "≠Visited": does not equal Visited. (Don't use "=Normal," because every state is based on Normal.)
Be sure to connect those conditions with "or" (not "and").