That’s a shame. I’ve had no issues at all with mine, works brilliantly with my dura ace group set without having to adjust any gearing tension and the power accuracy has been pretty much spot on compared to my vectors. Sounds like you might have been unlucky with a duff product mate!
Also, I checked with JetBlack and TR support when I bought the product, both of whom confirmed it was perfectly fine to calibrate within the TR app.