loren,

A longshot: you don't have any hijack button code remappings/translations that might be coming into play, do you?

I made a mistake early on trying to add translations to pause and play based on mute line, before being educated/FAQ'd on the Emplode feature for 0V/12V, and saw similar non-deterministic behavior.

Another long-shot: are you feeding the mute line to just the empeg or to multiple devices? I've got two devices I mute from my speakerphone and had to add some protective diodes to prevent odd mute line behavior as things got warmer behind the dash.

-brendan