ibooks audio stops when image enlarged

I'm writing an iBook that requires readers to view images (music scores) made full-screen while listening to audio (in sound widgets). Until very recently, this wasn't a problem. The sound widget and the image co-exist on the same page; the user starts the audio widget and then taps the image to enlarge it. The audio plays while the user looks at the enlarged image.

Starting with the most recent iOS (I think!), that behavior has changed. If an audio widget on the same page is running, and you then tap the image to enlarge it, the audio stops. It's thus seemingly (and freshly!) impossible to hear audio while viewing an enlarged image.

Is this new? Is there a setting somewhere I need to tweak? Am I about to re-write a 200-page text with different widgets to get this to work?