Import animation from blender, transition info lost

I made a reload animation in blender, the mag is copy transform from left hand:
After exporting to unreal with send to unreal addon, it looks like this:
Seems like all mag’s transition lost, rotation and scale remains, or, may be, the transition data was scale down to 0.01, so it looks like lost, I don’t know why, I tried a lot of way to fix this , I’ve wasted 100 hours on this question.
Any know how to fix?

Copy transforms are not exported. Bake the animation in Blender

Thank you. It seems works.
But I saw a lot of tutorials about reload aniamtion, no one need bake manually, and when I bake manually with default bake settings, it not works, I turn on “visual keying” in bake setting, it works, what make my blender so defferent? btw, why I export animation before, “bake animations” option is turned on in export setting.

I don’t know what you do different but I always use visual keying and bake animation when I use bone constraints and want to export it to ue4 and it works fine.