ASUS Issues
See here for introductory information about manufacturer specific issues...
Overview
The latest ASUS devices have an app called "Power Master" that comes pre-installed. This app will block apps from starting and killing background tasks when your screen turns off.
Resolution
- Uncheck Mobile Manager > PowerMaster > Settings (or Battery-saving options) > Clean up in suspend
- Uncheck Mobile Manager > PowerMaster > Setting (or Battery-saving options) > Auto-deny apps from auto starting