@Tom_LeFx Did you set your plane as a static mesh? It needs to be static in order to be used for baking the lightmaps. I simply generated a plane in blender, imported in UE and assigned a very simple white material and it worked (though you need to tweak the various values for your scene to get a good result).
The spot, as noted above, should not use inverse square falloff if you are using the values provided by :
> “16 for the spots? So you are NOT using inverse square falloff?”
> Oops forgot to mention that ! I’m not using inverse square fallof for the spots (and the light fallof is set to 0.0001).