Next button doesn't work after Previous button used

Hi,

I am having similar issues to the above people but in Storyline 3. I have tried the above solutions with limited success. I think the issue is around the layers. I have lots of slides where when the previous button is pushed and it takes you back to slide with layers the next button then does not work. I tried added the variable but that causes the next button to not work at all. I think I am just missing something small but I can't figure it out. I have a large project with lots of scenes and it happening on all of them.  I have attached one of the scenes here to see if anyone can see what I am doing wrong. I suspect I am a bit confused about how the variables work.