MX1 to V16 - Aux Input issue

[LaneRM]

When connecting my MX1directly to my V16, I am unable to hear any audible alerts over the intercom. I am using the audio test function under the diagnostic page and I get the message "Audio phrases playback active," but I hear no audio phrases. My aux input is not muted, and I hear the attached clicking sound in the background regardless of whether I am doing the audio test or not. The sound is squelched when I speak over the intercom, and absent if I mute the aux input.

I have no feedback or any interference aside from what's listed above. Any ideas?

The only other thing I can think of is in the Serial Port Diagnostics page, for RS-232 Port 1(my V16 is on port 1) it looks something like this:

RX on EFIS Port 1: ?????????????????????? at number.number

The string of ?'s starts blank and then grows to about the size in the example above, then resets and does it again. The RX rate on the right varies up and down as you watch it. I don't know if this is related.

Thanks for any help.