Proper dynamic lighting in BSP requires additional lightmap data to be "baked" into the BSP which explodes filesizes. Then realtime ray tracing activates the lightmap shadow scaling which results in a shadow.
CSGO uses one dynamic light for the environment light source and allows a second light to be cast. When a third is added the lightmaps flicker around.
Edit:
I figure as the dynamic lighting from this plugin isnt compiled into the maps lightmap data it probably doesnt wig out, while they probably dont generate a shadow.