Here's my 2 cents:
My wife's iPhone X with iOS 15.3 has also been having problems with notifications. She found that WhatsApp, Viber and Gmail notifications were no longer working. Am guessing this started after the iOS update?
All notifications settings appeared correctly set on iOS and within apps, although notably WhatsApp was not listed within the iOS settings>notifications app list.
I tried:
- settings>general>Transfer or Reset Phone>Reset>Reset Location and Privacy
- launching What’s App & confirming permission permission to enable notifications.
- In the iPhone settings>notifications WhatsApp was now listed but notifications were still not working.
- Tried restarting phone - WhatsApp notifications were still not working
- Went to App Store - no updates were listed, but after I did a search for WhatsApp there was an option listed to update the app, which I did. This did not seem to get notifications working however.
- Went to location services in iPhone settings and set WhatsApp to 'always' on. Tested this by briefly sharing location from my wife's phone to mine. After this her WhatsApp Notifications finally started working. Not sure why it took this last step.
Now I just need to try and get Viber and Gmail notifications restored.. Gmail notifications on locked screen are missing, despite iPhone settings suggesting they should be there, and all Viber notifications are also not working.
Rodger