I’m puzzled by this intermittent background shortcut

I’ve been testing the following shortcut. It’s intended to automatically keep pausing a foreign language podcast every 10 secs to assist learning and will keep going when I’m out running with the phone screen off in my pocket.
The Play Sound action seems unnecessary but if I remove it the shortcut stops working in the background. It also fails if I try to improve the order logic of the actions.
I guess this is just Shortcuts being buggy but if anyone has any thoughts I’d be interested.

Shortcuts cannot run indefinitely in the background. Audio playback can, so by triggering the audio playback, it can keep running even when your device is not in active use. It’s a workaround people have been using for several years to get around the restriction. In fact app developers have used it too, playing silence - Facebook was probably the highest profile one to get in trouble for subverting that permission.

Yeah thanks. I think that’s why I did it in the first place but then got confused.