How accustomed to riding ERG are you? There’s certainly a bit of a learning curve with holding steady.
Also, what is Trainerroad reading power from (Stages or Direto) and are you using power match? I find with the Elite trainers, especially optical sensors, there is a pretty annoying lag between your power output and adjustment on the flywheel, leading to yo-yo’ing. My suggestion would be make sure your power meter is NOT paired to your Elite, and make sure TR is reading your Stages power meter with power match.
Lastly why are you more inclined to believe your Elite over your Stages? Should you choose to use the Elite, I would be very diligent when calibrating.