I'm having the same problem have you found a solution?

On the fenix 6x pro I found a solution. If you open the indoor bike activity and hold the watch close to the ant+ logo on the echelon 2 it should show that the power meter was added. This worked for me but it drops data pretty frequently. I have called Garmin about it and they said they will look into it. This will only work with mpower echelon2 firmware version 1.7 and not with version 2.9.

The Echelon is at the gym but I remember my Fenix 2 I had to disable Bluetooth to get Ant+ to work or vice versa.  However, it warned me.  I don't see that on my new Forerunner or in the manual (don't recall it was in Fenix2 either).  I'm going to try this next time and disable Bluetooth first, per:  

Turning Off the Bluetooth^® Smartphone Connection

I suggest trying what I did if you haven't already.  The echelon2 doesn't appear to pair through the pairing function on garmin and only directly through the activity itself. 

Could be it doesn't transmit until you're doing something that would make it transmit.  It's like footpods and HRM bands where you actually need to wear them to pair.

Just got a Schwinn AC Power spin bike with the Echelon2G console and a 4iiii power meter (left crank only, dual not available). Current firmware is A2.0 V2.9, which is the latest firmware available from the Core Health and Fitness support portal. The Echelon and Echelon2G use the same firmware per the download site from Core. Sounds like pairing for data export to a device requires ANT+ FE-C available on the device, which is available on the Edge 830. Paired first try, but instead of searching for a sensor, need to go to Training > Indoor Trainer > Pair ANT+ Bike Trainer. Didn't see any analogous menu options on my Fenix 6x pro sapphire for indoor trainers, and no sensors detected with the Echelon2G turned on. However, turning the cranks activates the 4iiii power meter, and that successfully linked to the Fenix 6x. I had wanted to be able to export workout data to either the cycling computer or watch to get cycling VO2 Max, FTP, lactate threshold for indoor workouts, and contacted both FirstBeat and 4iiii tech support prior to the purchase. I was told that as long as HR, power and cadence are available, those metrics would be available. Worst case scenario would be connectivity to the power meter only to the Fenix 6x, which would get power and cadence, with HR from the chest strap, so would be adequate for those metrics, although the other data that is generated by and displayed on the console during a ride wouldn't be saved. Don't know if the power meter used on the older bikes at the flywheel is ANT+ to get similar data. Let me know if I am missing something with the Fenix 6x, as I'd rather wear the watch to record data during the ride than leave the Edge 830 mounted on the aero bar section of the handlebar. Haven't had a chance to ride it yet with the Edge 830, but have temp added a speed field to the indoor cycling screen to see if speed will be calculated and displayed. No speed display on the echelon, only power, cadence, time, distance and gear, as Schwinn claims speed is not relevant for spin rides. will also see whether gear displays, but expect that would be limited to Shimano or SRAM electronic shifters.

Have you ever used the mpower echelon 2 and what software version if you have? 

no, just the echelon 2g, but with the firmware noted above

I just picked up a Schwinn AC Power indoor cycle, and so far, all the power metrics are transferring to my Garmin Fenix 6S Pro with the exception of Distance.  Is there any way to get this metric to the watch? 
Power, Cadence, Speed, etc. are all transferring beautifully, but it's annoying when at the end of a workout, the Distance field is blank.  I've been manually adding it to the workout-session using the mobile app, but doing it that way doesn't transfer the Distance data to the other apps I have linked to Garmin Connect (Endomondo, MyFitnessPal, etc.)