I assume that it will play the sound when you access it via IE browser?
I’m asking about IE, because Xibo emulates IE11 to access webpages on a layout.
Could you double check browser emulation settings please and make sure there is a full and correct path, as there is a bug with it in 1.8.2 - https://github.com/xibosignage/xibo/issues/1281 (entries are not created in correct path).
Failing that, I’m not sure what else could it be, I believe we’ve tried some webpapges that play radio or straight up stream/video etc and that was working fine via Xibo as well.
Everything else besides the sound is correctly displayed?