I decided to turn off my bedtime routine and following some other suggestions I have read online disabled flip to glyph. The phone seemed to be working okay. I even started using bedtime mode manually and starred contacts were able to get through.
It has, however, happened again. I have missed all incoming calls and sms messages for the past 15-16 hours, including work calls which means I have missed shifts! Not happy!!
I think I have pinpointed the issue to when I used volume buttons on phone to switch to vibrate for a period of time and then turn back to full volume. I only realised I was not getting calls when my wife was trying to call me, phone rang out to voicemail multiple times so sent me a message via Messenger, I toggled flight mode on and off and hey presto 7 x sms messages came through, all marked at the time I received, not the time left. This included 5 x missed calls, 1 x voicemail notification and 1 x message.
This issue is really starting to get annoying, especially as it is costing me money by missing out on work!!! Starting to regret purchase of phone.