Hello,
We are aware of this issue and we keep improving reprocompatibility as we get more V2 scenes for testing. However, we recommend that when working on a production you finish your project with a single version(don't update to a major version).
Please send me your scene for testing and debugging. You can send it to jeordanis.f (at) ephere .com. Simplify the scene as much as you can and only leave the problematic hair object and it's dependencies(like hair maps), also include a description and a link to this post. Thank you.
NOTE: Have in mind that V3 is still in beta.
Jeordanis Figuereo (Product Designer. EPHERE Inc.)