Once published, sound plays only on 1st half of slides

Hi. I've published the training and am watching it online. The first 27 slides play as they are supposed to - I can hear the audio I recorded. 

When I'm in Articulate I can hear the audio on all slides, but on the published slides, no sound plays after those first 27 slides.  More than half have no sound.  Is it something to do with lock/unlock?  I tried to compare the slides that work with slides that don't work, but I can't tell the difference.  Thank you. 

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