This is most likely a consequence of this bug fix, and the associated changes we made at the time. It’s a long story, but in essence, the default cutoff is now more appropriate for the output of dwi2fod msmt_csd than for the regular dwi2fod csd (which I assume is what you used here?). You should be able to get close to your original results by adding the -cutoff 0.1 option to your tckgen call…