When precomputing multiple scenes sometimes the localfileID of the lightingdata asset reference in a scene file will change. This will happen even when the number of scenes involved in the bake doesn't change. This is a problem for teams that use perforce and have exclusive check out turned on for scene files. Prevents a build machine from checking in bake lighting results and results in broken light bakes. Really big productivity issue for any team baking lighting and using perforce.

I "think" the following code in WriteLightingDataAssetJob.cpp on line 211,

// Get rid of existing LightingDataAssets
if (m_OnDemandBake)
LightingDataAsset::DestroyLightingDataForLoadedScenes(false);

maybe the cause of this. Don't think it's guaranteed for the lightingDataAsset to be assigned the same instance Id after deletion.