yesterday I experienced the same. My companion App was showing let’s say 175 Watt and on screen the Apple TV showed 160 Watt.
I had the feeling that there was a delay between the Watt shown in the App and the Aplle TV of about 1-3 seconds.
Maybe this has something todo with the fact that I have paired my Wahoo Kickr (Power and Cadence) and my Wahoo Tickr X not directly to the Apple TV but to my Iphone which Iam using to run the Companion App. (Not sure)
What I will try next time is to turn of bluetooth on my iphone and then pair the wahoo kickr with the Apple TV directly (for Power).
Then my setup would be:
Kickr Power + Bluetooth Headset + Apple TV Remote = paired with Apple TV
Kickr Cadence + Tickr X Heartrate = paired with Iphone via Companian App