Ok, if you have 7 UV Maps that leads me to think that your leafs are in a separate map and aren’t getting light information baked to them.
My suggestion would be to open up your asset in blender, delete all the UV Maps and create 2 new ones. Then unwrap your mesh using the SmartUV Project tool and create 2 identical UV Maps. Export that to FBX and reimport it into UE4, set your Lightmap to UV map 1 again, then try to bake.
I’m not sure if UE4 would know what to do with 7 UV Maps. In my experience I use 2. Channel 0 for all of my textures and Channel 1 for lightmaps.
Edit:. Bake = Build Lighting