Messages don’t appear until I unlock my phone…

Messages don’t appear until I unlock my phone…

My iPhone 13 Pro will vibrate and ding as a notification from all apps within 15 minutes of the phone being locked and on Lock Screen, including iMessage and text message.

All Lock Screen banner notifications are set to off - only audible notifications are set to on.

However, approximately 15 minutes after the phone is locked and someone sends an iMessage or text message to the iPhone, it will not vibrate or ding — until the phone is unlocked.

Suddenly the phone will vibrate and ding with all iMessages and text messages received, simultaneously.

These messages show they came through to the iPhone, sometimes, from hours before.

This is evident because the messages have the specific time they were sent attached to them.

After calling Apple, they suggested a restore to the phones network settings.

That didn’t work.

Then they suggested a reset to all settings.

The only phone setting changed after the reset were the settings that should have stopped the apps banners from appearing on Lock Screen.

This didn’t resolve the issue either as the phone is still not vibrating or dinging when messages are received, again, after approximately 15 minutes of the phone being locked.

Why is my iPhone 13 pro, after 15 minutes of being locked, not notifying me of new incoming messages VIA its vibratory or audible function?