Chinese Roms in my experience kills the app in the background no matter what I do, I changed to let it run in the background, put a lock in recent apps and put a priority in notification, and it still kills the app that I wanted to keep on memory. Flyme 6 and 7. Apps were meditation timer and 3rd party music player. Now I'm going back to Flyme 6 Global due to better battery when I've installed Google Apps