PrVELO (v1) tracks do not have their chi2 or ndf filled
All velo tracks should have had a Kalman filter applied to them, assuming pT = 400 MeV.
While this fit is a bit premature, the result of this is still a chi2, in addition to the state. However, this chi2 does not seem to be propagated to the track itself, nor the v1 VELO tracks available for analyses.
(This could have been done on purpose to save space for the velo tracks, if so, this issue can be a 'not fix' @ahennequ )