This thread is from over two months ago that I just came across, I’m not sure if you are still experiencing this but nevertheless…:
I am not sure, but I have heard that sometimes if your device has a lack of storage it may interfere when playing an episode story heavy on music/overlays etc. which may result in not being able to achieve the greatest reading experience.
ALSO
have you checked if you have coded the sound appropriately in your script. there may be a fault
lastly, make sure to turn your ring/sound of your device on. if your ringer/sound is off, you may not be able to hear the sounds…