On one of my Macs (of 3), the volume control on MC disappears and becomes unresponsive and nonfunctional when playing. When I start up MC the volume control is there, but when I start playing, it disappears and MC plays at full volume. It acts like it can't make a volume adjustment.
I've been running MC on this Mac (specs below) for years. This bug is new for MC 30. MC 29 still works fine on that Mini, volume control is fine.
MC 30.0.18 (the first and only MC 30 I've run)
2014 MacMini, macOS 12.6
Audio out via HDMI
The attached photo shows MC with no volume control. It's playing, with the audio at full volume.