Muse Sounds Not Working

Over the last few months, I have installed Musescore on three different computers, all running Windows 10 or 11 64-bit. I have then proceeded to install Muse Sounds, via Muse Hub, on all of these devices. Muse Sounds, however will not work. On all of the devices, I can open Musescore, start a new score, go to Mixer and select any Muse Sounds instrument - they're all there - but they won't make a sound when I attempt to play them using either the Piano Keyboard function or my MiDi keyboard. What is going on here? (Musescore basic sounds are all working fine, for the record). Note that, on all devices, if I go to View> Playback Setup, it shows Muse Sounds as "Active" and "Set as default for new scores", but this doesn't seem to be the case.