This is something that's really getting annoying now. I have a Huawei P10 Plus (and this also happens on a Huawei Mate 9 as well) to the point of some notifications (Ring doorbell) being lost. I know of these not happening because I have a Vodafone Smart V8 for testing and while nothing shows up on the P10 Plus, the Vodafone device happily shows the notification.

All the battery saving settings are turned off. For example I open a couple of apps at night before going to bed - when I get up in the morning and look at the tasks running there aren't any - all apps are closed.

This is specially annoying with Ring, Tile, Life360 which are apps that need to be awake to update location, etc. Also Health Mate (Withings) which doesn't sync my watch automatically unless it's running but it keeps getting closed.

Interestingly notifications for other applications won't fail - Messenger, Signal, Facebook, Twitter.

On my Vodafone V8 test handset apps will still be in the task list even after a restart. 

Any ideas on how to change this behaviour?