Converting BSP to static mesh


I’ve started working with brushes and have run into an issue. I’m trying to make a pipe that I can roll a ball around in, so I grabbed a cylinder brush, set it to hollow with 500 sides and messed around with it a bit. I can get the brush to work as intended - I can roll a ball around in it. Then I try to convert it to a static mesh. Suddenly, collision doesn’t work. I’ve tried messing around with the options for collision I can see when I select the mesh, and I’ve tried looking for answers but to no avail.

So far I’ve tried each of the collision presets, and none of them cause any interaction with the ball I’ve been rolling into it. I’ve also examined the collision settings from other meshes the ball will collide with, and copied them exactly for the pipe - still nothing.

I’m rather confused right now and would really appreciate some help. I feel like there’s something I’m missing, but I can’t find it.