Steps for reproduction :
-import a mesh with no UV sets at all
-put it in a scene as "static"
- use "Generate lightmap UVs" to generate unique UVs
- bake lighting with enlighten ( only baked direct and GI ).

Result :
After baking the lighting, the mesh is lit with lightprobes in the scene, no lightmaps have been generated for it.
Expected :
Lightmaps get generated for the mesh using the UVs generated by Unity, and are used in the scene (no lightpobe lighting).

This bug occurs in 5.5.0f1, 2017.3.0a8

Sidenote :
The bug also occurs on the 5.6 PVR branch when I choose enlighten as baking engine.
If I use the progressive lightmapper as baking engine however, this workflow works as expected : lightmaps have been generated for the mesh, using the UVs generated inside Unity.