False positive hits on BSP with single line trace

Alrighty guys, little confused on this one.

In my project I have created a ledge grabbing system using a couple ray casts to search for cases that I would like to “grab” and lerp onto. Everything has been working fine, I’ve pretty much eliminated all false positives (door ways, ceilings, etc etc)

I updated to 4.7 and everything continued to be fine. My level designer started blocking out a map in BSP and noticed the ledge grabbing was going nutso. I turned on some of the debug display for the rays and found that I was getting false positive “ledges” on flat BSP wall faces -but- its only SOME BSP and only in this new level my designer is blocking out.

I created some BSP in an older level, tested the system, everything is fine. Switch back to his level, some BSP volumes cause it to break and send me climbing up the wall, other walls in his level don’t have any problems. I checked to see if maybe they had a slight angle to them because of a moved vertex, I tried making new BSP surfaces
and I tried scaling them to be thicker, nothing seems to fix it. I also noticed on one specific wall I only got the false positive in the exact center line, scaled it thicker and they went away and I can’t get those to come back, wish I grabbed a screen shot.

Really not sure why this is happening or what is causing this to happen on SOME BSP walls.

Image attached should help explain some stuff, sorry if the compression has made the image hard to understand.

No help yet, admittedly its a strange problem, but it definitely seems like a bug that has popped up since 4.7.

To reproduce you need to raycast down along a surface, even if the surface is flat, you’ll get hits, that you shouldn’t get.

I’d say the problem is probably in the way you wire the blueprint rather than the line trace system.

Not sure what you mean here. The system works pretty flawlessly on BSP and Static meshes. 4.7 hit and it started misbehaving in only a certain level, then I was able to reproduce the problem on a few other pieces of BSP.

Ive tried the align to grid button, I’ve built geometry, etc etc. The only thing that fixes it is remaking all the BSP fresh. Thats all fine and good, but its still an issue on static meshes that are flat.