Hello,
Maybe is not the same bug reported by another user. Can you prepare a minimal scene where the issue is still reproducible?
Recently we had a bug where hair roots distribution will change when rendering in Arnold with motion blur, which seems to be the same case here. This was fixed on version 8 beta of Ornatrix and recently on version 7 as well. I just tried the scene that the user provided with the latest nightly build of Ornatrix V7(came a few hours ago) and I can confirm the issue is gone, but maybe you case is slightly different and needs further debugging.
Jeordanis Figuereo (Product Designer. EPHERE Inc.)