Huawei devices provide battery saving feature that shuts down applications when the screen goes off. 
Refer to the steps below to see if the problem is solved.

1. Tap [Settings] app → [Battery] → [App launch].
2. Find [KKBOX] and tap the button to the right to switch OFF "Manage automatically".
3. Choose [Run in background].
4. Tap [Settings] app again → [Apps] → [Settings] → [Special access] → [Ignore optimizations] → [KKBOX] and choose [Allow].