Struggling with 360 image Markers and Variables

Hi all. I hope someone can help. I'm normally pretty good with Variables and Markers etc. However working with 360° images is new for me, and it seems Markers and Variables do not work the same way inside 360Images. Here is what I'm trying to achieve.

I have a scene where you watch a video and then you're presented with 3 Casualties. You need to View all three casualties (by clicking on the Marker/Buttons) once done so, up comes a button (which was Hidden at first). This button will let you proceed to the Final slide.

I have attached the project file if someone can please help?

Thanks a lot.