How can I mute the audio from a video in Dorico?

Hello, pardon me if I’m not understanding something obvious, but I cannot seem to mute the audio (or even turn it down) from a video I’m playing within Dorico. In the Mixer I’ve turned down the video’s volume slider entirely, and also toggled the Video’s “mute” button. Nothing seems to make any difference. What am I missing?

It really should be as simple as muting the video track in the Mixer. Can you reproduce the problem with another video file in another project?