Blackview

Pin the App in the Recent Apps List

Open the recent apps screen > tap the ellipsis next to the app name > select Lock > in the allowed apps list, tap the lock icon next to the app.

Disable Background Activity Restrictions

Settings > Apps & notifications > Show all apps > select the app > Advanced > Battery > Background activity restrictions > Off.

Disable Automatic App Memory Cleanup

Smart Assistant app (or Management) > App management > Automatic memory cleanup > toggle off for the app.

Allow App Auto-Start

Open the Basic Maintenance app > App Manager > Auto-start > select the app > On.

Configure Power Saving Settings

Basic Maintenance > Settings (gear icon in the top right) > disable Smart power saving in sleep mode.

Add the App to Battery Optimization Exceptions

Settings > Apps & notifications > Special access > Battery optimization > select All apps > find the desired app > set to Don't optimize.