Black play button when adding Storyline content to Rise

I am adding Storyline content to rise, that does contain video, but not until slide 2. 

Despite that, I get a black screen with a play button overtop of the Storyline interactive before the learner can begin. Why? There is nothing to play until slide 2. 

There have also been times I've published courses and this black screen does not appear, but I have not changed the settings at all.

I am going insane. Please help. Thank you