After selecting a music file to open in file explorer in a floating mode, the music stops as soon as the phone is locked. I whitelisted both the player and explorer in battery saver settings but no luck. Playing music in the music player itself isn't creating this problem, though.
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Edit: The device is Redmi 5 plus but it's on a custom rom (Havoc OS 3.3, Android Q). The music player is Hash Music Player