I had suffered this problem from foliage, InstancedStaticMeshComponents as well.
However have found a solution to fix it in 4.7.6.
- Open ‘World Settings’.
- Goto ‘Lightmass’ category.
- Check ‘Force No Precomputed Lighting’.
- A popup will appear. Press ‘OK’.
- Press ‘Build All’ or ‘Build Lighting Only’. Static Lighting will be crack. That’s OK.
- Save the map.
- Reload the map. Open another map and open the map or double click the map in content browser.
- Lightmaps will be 0 in Lightmass categoty. If not, load the map again.
- Uncheck ‘Force No Precomputed Lighting’.
- Save the map.
- Press ‘Build All’ or ‘Build Lighting Only’.
- Solved.