Steps to repro:

1. Download attached project - https://oc.unity3d.com/index.php/s/qmGgVmvCEHrZPlY
2. Open 'LightMapTest2' scene;
3. Launch the scene - observe that the lightmaps are rendered on static gameobjects as expected;
4. Open 'LightMapTest3' scene (same as 'LightMapTest2', but the scene's main prefab is loaded via Asset Bundles;
5. Observe artifacts and inconsistent rendering in both Scene and Game view, comparing to 'LightMapTest2' scene.

Expected result:
Scene rendering is consistent with 'LightMapTest2' scene. See attached 'correct(scene2)' screenshot;

Actual result:
Scene's rendering is inconsistent with 'LightMapTest2' scene: there are artifacts in the Scene view and significantly lower light intensity on scene geometry's surface. See attached 'incorrect(scene 3)' screenshot.

Notes:
- Reproducible in 2018.3.0a9, 2018.2.4f1, 2018.1.9f1, 2017.4.9f1;
- Reproducible on Windows 10, asset bundles are not loaded on OSX.