Same issue. It turns out that do not disturb mode on my phone got turned on somehow. It would still allow the notices to come through to the watch but was overriding all of the sound options on the watch. Hope that helps.
I did run through the usual troubleshooting steps first:
1) restart watch
2) restart phone
3) make sure apps are up to date
4) reinstall Samsung apps on phone
5) factory reset Galaxy Watch
... View more