Hi,
I have issues using the node Apply Mesh Additive in my Anim BP and I would really appreciate any help 
1- When using Mesh additive + Frame on this animation, the additive seems to be played in mirror.
The feature on which i am using additive is hit reaction. Left And Right. But when I use Additive Left, the character goes Right. Feels very weird so my workaround was to inverse those Additive anim and it was fine. I don’t know where it comes from.
2- The other issue, the real one I want to solve, in fact, is that this Apply Mesh Additive node, seems to not work at all for bones that are not under my Root_M.
For example, I have two kind of Skeletal, some with weapons bones under hands, some other with weapons bones not under hands, so independent, like Unreal_Root > Sword next to Root_M and not under it.
For characters who have weapons bones under Root_M, it’s fine, but for characters who have weapons bones just under Unreal_Root, it’s not good, weapons are not linked visually anymore to hand while the additive is played.
If someone has already encountered this issue… Also, what kind of methods are you using to play hit react ?
For my needs, Additive is the node i want, because blend are not working as my character can do everything he wants during it (I have also interrupt and stun feature, but hit react is just a feel element).
Thanks