Steps to repro:
1. Open attached project and 't1' scene;
2. Open Lighting window (Windows>Rendering>Lighting Settings);
3. Clear Baked Data and GI Cache;
3. Click 'Generate Lighting' button in the Lighting window;
4. Wait until baking is finished;
5. When Lightmap baking is finished open Global Maps tab of the Lighting window;
6. Observe the window.

Expected result:
There are no Intensity and Directional lightmaps baked for this scene.

Actual result:
Empty lightmaps are baked for the scene. See attached actual.png screenshot.

Notes:
- Reproducible in Unity 2018.2.0b3. 2018.1.0f1, 2017.4.f1;
- Reproducible on Windows 10 and OSX 10.13.4;
- The issue doesn't affect lightmapped object rendering;
- The issue doesn't happen with Enlighten.