With "boarding sound", you mean the background sounds, or the attendants greetings ?
Sorry for the slow response. Never got a notification even when I checked that option.
I think the issue might in fact already have been fixed. As I recall from recent flights, I've had the sound also on additional legs and not the first one. Will make sure to pay attention to it and let you know if the issue still is present.
As for what sounds, again as I recall it, I suppose it was mainly the attendants greetings which were missing but maybe some sound of the passengers boarding as well. Don't recall what exact sounds you usually hear during boarding, only how it was very quiet on seconds leg vs the first leg during the boarding phase.
