BSP and the Amazing Disappearing Sprites

[Da Werecat]

Sprites disappearing when you reach the limit are hardly anything special. When I saw it in my latest map, I immediately thought that I went overboard with sprite trees. Which I kinda did, so I started removing and rearranging them.

At some point I noticed that the amount of vissprites reported by Chocorenderlimits doesn't make a lot of sense. So I removed some sectors, sealing the player start in a location with exactly 0 objects. I got 70 sprites. Then I walked around and maxed them again. Yeah, what?

I switched to ZenNode, and sprites still "leaked" through solid walls, but this time there were much less of them - around 10, which is manageable. The only problem is that ZenNode gives me a big HOM in one of the less orthogonal rooms. I guess I can move some vertices around, but I'm curious: is there any way to make it work with BSP-W32? Maybe there's something wrong with my map? Map Analysis Mode didn't show any errors.