Generating Lightmap UVs Freezes Unity

I have an FBX file consists of 100+ models. When I try to generate lightmap UVs for this FBX file in Unity, by checking the Generate Lightmap UVs in the Model Import Settings, Unity always freezes.

Is there another way to generate lightmap UVs in Unity?
Or is there a better way to generate lightmap UVs, outside Unity, by using other 3D softwares?

Does it freeze, or does it simply take a really long time?

You can always make your own UVs in any 3d software.

In the past we had issues with large meshes. As unrelated as it sounds, the size of the mesh had a huge impact on the uv mapping peformance up to the point where it just crashed. By size, I really mean the size of the mesh, i.e. how large it extends in the scene, not how many vertices it has, or the filesize of the mesh.

If you can try to reduce the problem to see what (possible single) mesh is causing the problem.

It froze, because I waited for more than 24 hours. Finally I shut Unity down forcefully by using the Task Manager.

I think Unity’s automatic lightmap UV generation feature cannot handle a complex FBX file that consists of hundreds of models and millions of polygons. I will try to split the FBX file into several FBX files.

I hope this problem will solved in this following link problem - Generate lightmap UV - unity