BlueWhale627 wrote:
The iPhone no longer plays any notification sounds when the iWatch is paired. If unpaired, the sound returns.
However, the ringtone still works for incoming calls when both devices are paired.
That's correct and exactly how Apple intends notifications to work. Just an FYI, it's not iWatch. It is called Apple Watch. When your iPhone is screen is locked and you are wearing your Apple Watch, notifications are delivered to your watch. If your iPhone is screen is open, notifications will be delivered to your iPhone. But notifications will NOT be delivered to both at the same time, except as you've noted, phone calls.
Read this link to better understand notifications with Apple Watch --> Notifications on your Apple Watch - Apple Support