Slides add time at the end

In Storyline, my slides are set to advance at the end of the audio file.  I publish and it works wonderfully in a browser window.  It also works just fine on our LMS.

Mobile.  When I play the course through our LMS on an iPad, 10 seconds or more pass between the last of the audio and animations before the slide advances.  I've adjusted the audio, I've republished.  I've published AICC.  I've published SCORM 1.2.  I don't have time or budget to create two separate courses.  That's why there is html5 output, right?

It's like the seek bar has its own timeline away from the actual timeline I set in Storyline.  The slide finishes playing and the seek bar just continues on with silence and we wait for the course to advance.  Because this can't be seen in Storyline, I don't know what to fix in order to the get the slide to advance when it is actually done playing.  Could it be as simple as removing the seekbar so that rendering doesn't even have to take place?