Steps for reproduction:
1) Download the project below
2) Open the scene `ProgressiveLightmappingExample` scene
3) Bake the scene
4) Open Baked UV Overlap section in Object Maps
5) In Hierachy find `Signs01` and `Stalls04`
6) Select the objects
7) Observe that lightmaps won't load in Object Maps and other objects successfully load in Objects Map window.

Notes:
- Not a regression since the feature is recently introduced in 2018.1