Go to settings > client settings, enable the background audio with the checkbox:
That definitely does not fix the issue. Not sure if it is just certain devices or Android versions or whatever that have that issue, but having that checked makes no difference for me in recent months. Even with that setting enabled, if I start playing a video then switch to another app, the audio keeps playing for three seconds or so and then just cuts out. The video keeps playing in the background, but no audio.