Cannot set LightMapResolution neither LightMapCoordinateIndex on fresh imported mesh

I’ve imported some fbx files using

FAssetToolsModule& AssetToolsModule = FModuleManager::LoadModuleChecked<FAssetToolsModule>("AssetTools");
TArray<UObject*>  ImportedObjects = AssetToolsModule.Get().ImportAssets(files, myPackageName);

I cast them to UStaticMesh and apply materials without problem etc
UStaticMesh* sm=Cast(ImportedObjects[m]);

But this two values are ignored ie

sm->LightMapResolution = 128;
sm->LightMapCoordinateIndex = 1;

When I open it on the editor coordinate index has been reset to 0 and lightmap resolution to 64 (default values)

I tried several things like


But I had no luck, I’m driving totally nuts with this.

Any luck? =)