I had this issue with my Kickr & Garmin pedas setup when I first started using TR. Was driving me crazy.
Once I started calibrating both the Kickr and the pedals before EVERY ride it went away. Don’t know if it was coincidence, but that was my solution. Initially, I thought I just had to calibrate the pedals as the power source, but the Kickr’s calibration proved as important. I use an ANT+ dongle with my laptop.