First, I'm sorry for my bad english.
I own a BV4900pro since 6 month.
Android is up to date.
Since the begining, I'm unable to keep my apps working in background. I set to OFF the battery manager for theses apps, but after a few hours, theses apps are not running.
Facebook, Messenger, Outlook, Ebay... i'm unable to keep one app alive all day long. And i miss very important notification.
I searched in all settings menus, nothing about that.