I recall.. that the exclude and include work differently for the type of light source you use...   use a different light source and you might see a difference...   a spotlight's properties might not work the way you think using exclude or include functions..

 

suggestion:

This is a good time to set up an experiment on this...  using different sources...

set up 5 spheres, name a to e, in a circle on the plane put a source light above and center and play with the exclude and include functions..   see the results...

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