Hello GoodFry,
As restarting both devices didn't resolve things, there are a few other steps to try.
First, ensure both iOS and watchOS are up-to-date fully, after backing up the companion iPhone to help preserve data.
You can update on each device at Settings > General > Software Update. For more info on updating check out this link: Update your iPhone, iPad, or iPod touch
If updating doesn't help, you may try unpairing, and then re-pairing the Apple Watch and iPhone. This page here will have the needed steps in the "How to unpair your Apple Watch from your iPhone" section:
Unpair and erase your Apple Watch
1. Keep your Apple Watch and iPhone close together as you unpair them.
2. Open the Apple Watch app on your iPhone.
3. Go to the My Watch tab and tap All Watches.
4. Tap the info button next to the watch that you want to unpair.
5. Tap Unpair Apple Watch
6. For GPS + Cellular models, choose to keep or remove your cellular plan.
7. Tap again to confirm
Then, you can find info on setting it up again here, if needed: Set up your Apple Watch
If nothing above helps, you may try reaching out to Apple Support directly for a deeper investigation via this link: Get Support
Cheers.