There was a similar post regarding 3.0.9 Nightly version not being able to play some HLS audio streams. ( https://forum.videolan.org/viewtopic.php?f=14&t=151610 )
Not sure if that's the case here, but today, I upgraded my VLC to version 3.0.10, and noticed that, although I am able to play recently downloaded mkv videos normally. there were some older mkv videos I had whose audio wasn't working at all (like the audio tries to play at the beginning but it immediately stops working). For a moment I thought those videos got corrupted, but I then tried downgrading to version 3.0.8 and it worked just fine. It also works on Android Version.
So my guess is that Version 3.0.10 is having some codec issues but, to be honest, I don't know much about technical details regarding this kind of software.... So there is not much more info I can provide unless someone tells me where and how to retrieve it.
Should this be reported as a bug? Or there is something else I am overlooking? I tried messing with preferences and still couldn't make it work, and as I said, other videos did play normally. (I downgraded and upgraded twice just to make sure, btw).