"L/R power balance data will only upload into Garmin Connect from a Garmin watch or Edge cycling computer paired to a Tacx NEO 2, NEO 2T, NEO Bike, or NEO Bike Plus smart trainer."
The Neo 2T broadcasts cycling dynamics, but you need a watch that supports cycling dynamics to upload to Garmin Connect. I just got my Neo 2T today and got the Yin and Yang badge :) using my Garmin Descent G1.