Why do volume buttons not work when screen is off/locked.

[Android Central Question]

Hi, I have a Huawei P20 Lite with EMUI 8.0 based on android 8.0.

I often listen to podcasts and music, or connect to chromecast.

I would like to be able to use my volume buttons when the screen is locked/off.

The reason is because I don't need the screen at all when listening to something or watching on another screen, and it's an extra step to wait until the screen unlocks.

I can't seem to find a setting for this anywhere. Anyone have a clue or a solution?

Thanks!