Playback not working on Kubuntu 21.04
I've just started using Musescore on my new computer and I've been experiencing a major sound issue: the playback function doesn't produce the chosen instrument sound, but just an awful scratching noise (repeted twice for each note). The noise is the same for any instrument.
This happens in any version of Musescore I tried: 3.6 (appimage), 3.2 and 2.
My system is Kubuntu 21.04.
Everything was working fine on Lubuntu 20.04 on my OLD computer (which I used until four weeks ago).
I have no idea if the issue is with my operating system (some missing libraries, etc.), or my hardware.
Sounds reproduced in any other application are working fine.