Tracking the completion of layers in a slide

Hi everyone. I'm struggling to keep tracking on one particular slide. I have eight layers in one slide accessed by eight icons, most layers contain a video. When each layer is opened, I have triggered a variable to change to show that that layer is completed. When I close the eLearning then resume later, I get taken to the correct slide, but all of the icons revert to their original state. I have 'Resume saved state' checked in the slide properties.

Any help greatly appreciated. Thanks, Lee.