Not sure if this is a bug, but I did want to make you aware of this, if you use an xrefed object with ProOptimize along with the velocity channel, it takes aaaaaaages to parse the scene, and on rare occasions does it actually flag up the error "geometry motion blur is not supported on meshes with changing topology".
The easy solution is to just collapse the mod stack on the object, but maybe the timing of the velocity channel and the loading of the object at render time is the wrong way around?
