So on my project I have trees from the updated version of the country side asset pack from the marketplace. So I have the sky light set pretty dark to make it night and when I build the lighting, the trees are dark like they should be in SOME parts. Other parts of the trees are bright like if there was light shining on them. I even lowered the light map and it fixes some of them but not all. I built the lighting with and without an importance light volume and it didn’t make a difference. And I’m using UE4.8. Any way to fix this?
since this is an asset pack, you may not get much response unless you paste some detailed screenshots of the issues as well as how the materials and lighting are setup. The problem is without knowing what kind of assets you are dealing with, I have absolutely no idea what to suggest, so you are basically hoping somebody else who used the same pack and ran into the same issue and solved it will reply, which is probably not too likely (but not impossible 
This is the asset pack that I am using. In the pack it has a folder named “Legacy” for the older versions of the meshes but I am not using those meshes. I am using the updated ones.
And this is what happens when I build the lighting with and without the lightmass importance volume. The sky light is down to 6 and the trees are the only things that look like this. Is there a way to fix it?
looks to me like invalid lightmap UVs. can you check what the lightmap UVs look like? you can check by double clicking the assets and seeing what lightmapcoordinateindex they use, and then use the Preview UV button and select that channel from the drop down list.