Just got the word from a Meridian tech support guy. It's a bug in the current version of ControlMac. They are working on a new version to address it.

As a data point, it works on a laptop I have running 10.7.3, but not on my 10.7.4 iMac.

I didn't get enough detail to know if the dot-rev was the problem.

Thanks to all who pitched in on this one.

Living room: 818v3, Parasound A23+, Maggie 1.6
A/V room: 861v8, DSP7200SE L/R/C, 4x DSP320 surrounds, ID41 + Roon, UHD722, Prime+PS