Muted Brass with Muse Sounds

With MS Basic, I've been able to apply mutes to trombones and trumpets and the playback changes. This doesn't seem to work with the recent Muse Sounds.

I've tried the two mute options ("mute" text and the "+" from the Pallettes menu) with Muse Sounds but the mutes don't work.

I've already checked the MuseScore 4 handbook, but I have not found anything useful with brass mutes.

Is this a feature still yet to be implemented? If so, please mention when?

Attached is an example file with the mute text option.