Slide Masters and Full Screen captures

I have built a Menu as a layer on the Main Slide Master in Storyline 1. I can get it to work fine across all slides except those that have full screen system captures. I even masked out a transparent area for the custom Menu button to appear. This makes the Menu button visible but it's not clickable. I've looked at formatting the background, looking at layer properties etc etc but have not found a solution to this problem. The only way it will work is to crop the system capture images so the whole top section is visible but this takes up too much of the system screen. Any solutions greatly appreciated. I'm an experienced user but can't figure this one out. Happy to look at any options.