Hi , thank you for your reply.
I know only the right hand animates, that’s ok and I was aware of the scale being very high. I don’t think that’s an issue for UE4 since I used this exact same model and rig (with a different animation) in an older version of UE4.
Also I can see in your image that it does not animate properly because that’s a frame that does not exist in the original animation. You are having the same issue I am having, the pointy finger for example never bends and in the .fbx, it does.