Good morning.
I recommend that you start restarting your iPhone like this:
iPhone 8 and following:
Quickly press and release the Volume Up button
Quickly press and release the Volume down button
Long press the side button (power) until the Apple logo appears
iPhone 7 and 7 Plus:
Press the Volume down button and the Side (Power) button simultaneously with a long press until the Apple logo appears
iPhone 6s and following:
Long press the side (power) button and the Home button simultaneously until the Apple logo appears
Then I suggest you restart your Apple Watch too:
1) Hold down the side button until the power button appears in the upper right corner of the screen.
2) Tap the power button.
3) Drag the shutdown slider.
4) After the Apple Watch shuts down, press and hold the side button again until the Apple logo appears.
That should solve the problem. If it persists, make sure you have the latest version of iOS and watchos installed on your devices.
If that doesn’t help, try disconnecting and reconnecting your iPhone and Apple Watch (reconfiguring your Apple Watch from scratch).
I hope I helped you!