I apologise. I didn’t mean that it’s an actual Hammer issue, just the way that UE4 handles all of the brushes. If I were to model entire rooms as one large mesh I don’t think it would be nearly as noticable as having a room built out of several brushes. Yes I could group them all but then the lightmap UVs would be messed messed up. All of the answers I see on the forums just say “don’t over modulate your maps”. It’s really a shame that classic BSP style mapping isn’t as popular in modern engines 
I’ll try playing with it some more. The plugin itself is really fantastic and I thank the OP for his work on it