Hi
The following steps may help:
If you have not yet done so, update your iPhone and Apple Watch to the latest software, starting with your iPhone:
Check that you have installed the latest version of the app on your iPhone (via the App Store).
On your iPhone, in the Watch app, go to: My Watch (tab) > Sounds & Haptics:
- Check that the Alert Volume is towards the centre or right hand side;
- Check that Silent Mode is not enabled;
- Check that haptic strength is set to the middle or far right hand side of the slider.
On your watch: when viewing the time, swipe up on the watch face to open Control Centre > check that Do Not Disturb is not enabled (the button with the moon icon).
Check the notification alert settings for the app on your iPhone:
- Go to: Settings > Notifications > check that all relevant options are enabled.
Restart both your iPhone and your watch, turning both off together, then restarting your iPhone first:
Unpair and re-pair your watch.
If the issue persists and you are receiving haptic alerts from other apps, I suggest that you contact the developer of the problematic app to advise them of the issue and to seek assistance with their app.