I frequently have this issue - I have a slide with layers, and I'm using the Show Layer Trigger when Timeline Ends. However, it isn't working and I cannot figure out why. As I said, this happens frequently, and I usually have to rebuild the slide.
Also, I have an image of a red Null sign on the base slide. This image shows up on the next layer, even though I have it unchecked in the Base slide timeline.
I've attached a file for your review and know in advance, your help will be greatly appreciated.