In this way, even if UE4 overrides my Lightmap, it'll override only the UV Map #1, which I wasn't using. The UV Editor toolbar contains general tools and shortcuts for working with UVs. Lightmap UVs settings We are seeing that unity stretches the UV when generating them for lightmaps, even if you create them in the 3d package.
then you need to do some settings based on scenes. 23 are working fine, and if a create a new project on 4. So as in below picture I changed 'scale in lightmap' parameter to different values until the UV. What I did as a workaround was to create a third UV set which was a duplicate of the Lightmap UV's.
Unity generate lightmap uvs not working If you have a problem, it's a great place to search for solutions and ask questions.