We are aware of current issues that are affecting the timing of the playback of MuseSounds within MuseScore Studio and have released a fix.
Close MuseScore Studio and MuseHub
Launch MuseHub and check for updates under the "Notifications" tab. The required update will install in the background.
Wait a minute or two for the update to apply
Launch MuseScore Studio
MuseScore Studio will also prompt you to update on startup if you still have an older version of the MuseSounds support library.