Vector 1 calibration way off despite doing static calibrations

For a few months the Vector 1s have been reading low, at about 60% consistently. It took me a while to figure this out because I was recovering from back surgery and had leg weakness. It’s not the Garmin 520 Plus because it’s also an issue with the Sufferfest app, which picks up via ANT+ and bypasses the Garmin.  I base the 60% on 1) comparing power for Strava segments done with same time, now vs previous, 2) setting Sufferfest to 60% achieves about the right intensity. I have not moved the pedals or Vectors. I updated Garmin software and do static calibrations each ride and it appears successful ie reads 0.03 or lower. What else can I do?