Blender to Unreal animations exported with rotation and location offsets on some bones


im currently working on character animations in blender and am creating animations for weapon reloads. I am using the rigify plugin rig.

I notice differences in some bones rotation and location between the blender animated version and the imported animation inside unreal engine. For some reason only the left and right thumbs are affected by this offset and i dont know where it could come from.
I tried baking the animation curves and keying every frame in blender, but the offset in the thumbs still persists.

For the moment i created an additional additive animation for the thumbs only that corrects the offset, but there has to be a cleaner solution for this. Does anyone know where the offset in the thumbs could come from and how to eliminate it? I attached some reference images for comparison.​​