Hi,
I can’t tell form here, but make sure that the lightmap channel does not contain any overlapping UV islands and has sufficient padding (that seems fine). Your issue seems like to be shadow bleeding, so I’d try to put the lightmap resolution to a higher setting, the default is 64x64, which is pretty small for any mesh with a decent size.
Here is a guide by Epic about proper lightmap creation:
https://docs.unrealengine.com/latest/INT/Engine/Content/Types/StaticMeshes/LightmapUnwrapping/