If have no idea what the root cause is, just that it circumvents the problem.
Have had the problem since quite some releases back, I think it was this post that led me to trying the disablement of pulseaudio suspend, and it has worked for me at least:
Like Keto wrote a few posts back, there seem to be a few different issues/behaviours causing trouble with audio, so the solution/workaround that solves it for me might not work out for everybody with audio issues?