Vacuum VI won't Freeze or Commit?

[Bushpig]

Hi All,

Just having my first go with PTHD12.6.1. Everything has installed and seems to be working OK. I'm just playing about and testing out all the new features. Loving the Freeze track feature, but I've hit a slight snag someone might know how to remedy.

No matter what I try, either Freeze or Commit, Vacuum (the standard free version) refuses to render. All the other basic VI's are behaving as expected, but Vacuum is not playing ball at all. PT goes through the motions, and disables the source midi track and also the Vacuum plug when it's done, but it finishes the task with a completely empty track.

Bit stumped. Might be something stoopid I'm doing (very likely).

Any help is much appreciated.

Steve Bush