Issues on playing HTML5 published files on iPad

I've run a Storyline module published to HTML5 on iPad Safari. One of the slides has interactions I inserted from the template. When I complete the interactions and click Next to the next slide, then click the "Back" button, the leftover of the layer from the last interaction on the slide is displayed and overlapping with the regular slide content.

This is just what happened on a simple "click and reveal" interaction slide. I had another test with interactions based on variables, and that messed up the screen even more when navigating to previous slides.

Has anyone experienced this kind of problem and any advice how to fix it?

Thanks much for any feedback.