Greenify auto-hibernation constantly being stopped

Hello everyone,

My Greenify constantly shows the auto hibernation being stopped message. I check every app and don't find any third party app that can kill apps. My device is Samsung s6 edge, rooted with xposed installed. I use boost mode in Greenify. I'm now wondering if it is killed by the android system? But some of my apps can keep running all the time, so maybe this issue is related to Greenify only?