MGL Extreme Thermocouples

[Onex107]

After 200 plus hours the thermocouple display on my MGL Extreme is going wonky. After starting the engine and idling at 1200 rpm to warm up the oil the CHT bar graph jumps from max to min to real on all four couples. The four EGT couples are normal. The odd thing is if I rev the Aerovee up to 2000 rpm they settle down to normal display. It appears that the anomaly appears and disappears with the increase or decrease from the alternator. All this time the battery reading is 12.6 and does not change. Only the CHT couple readings, nothing else displayed on the Extreme. When I fly and at cruise rpm the readings are normal. What do you think? Jump in everybody.
I disconnected everything from the RDAC except the eight couples and the ground to the engine block. Ran the engine and they registered nothing. No ambient, no numbers, no bars. As I added everything back one at a time they went wonky again. Has anyone experienced anything like this?

[XenosN42]

I used an Enigma in my Xenos and current use an iEFIS Explorer in my OneX, but I've never seen anything like what you describe. I would check and double check the grounding first.