iPhone not ringing when I watch is active.

You can open the Watch app on your iPhone ➔ Notifications ➔ Phone : Ensure that the Mirror my iPhone is checked.

Then, on your iPhone, open Settings ➔ Sounds & Haptics ➔ Ringer and Alerts : Make sure this is not set to OFF or too Low

Sadly, every time I've had notification issues relating to "Mirror Phone", I've had to do a wipe/reset of my phone and reconfigure the watch notification settings.

I've had to reset my phone at least 3 times because of notification problems, and have officially given up on using an Apple Watch because of how frustrating notification settings are. I do on-call work and I NEED to have notifications working properly. No one has been able to explain WHY the Mirror Phone function randomly stops working, so at this point, it's not reliable enough for me to trust my job with it.

If you decide to do a reset, make sure you back up your settings, files, etc, and take screenshots of your current watch settings (on the phone) before resetting your phone so that you can "easily" set it back up.