I have tried all the workarounds listed here. I have even done complete wipes and restored from MacBook backups, reset all settings etc.
Problem still persists.
iPhone 11 Pro Max running iOS 14.5.
The only thing that does work for me is turning Bluetooth off.
I have to make a choice between Bluetooth connectivity and being notified of incoming messages.
The UK COVID exposure app relies on Bluetooth handshakes so this lack of basic functionality could, in theory, endanger lives.
This is a major annoyance to me and many other people, but there are others worse off from reading the entire 92 pages of this thread, ie a blind person who relies on audible alerts, frontline workers with time sensitive issues to deal with etc.
Needless to say, I am very frustrated.
The hours I have put in trying to solve an issue which should not be on our shoulders.