Block is appearing in game, but isn't in hammer

First. forgive me for the large pictures.
This is probably an amateur mistake, but there’s a block showing up in game that isn’t in hammer.
This is what I see in hammer.

And this is what I see in game when testing out my map

(sky is black because I no clipped into the skybox)

I can also walk through it, and this is all I see

White skybox.

Anybody know what is causing this to happen?

You’ve got some pretty awful brush clipping issues there. Select all the wooden brushes around the edge and turn them into func_detail entities by hitting the “To Entity” button in the bottom-right of the Hammer window.

I’ve had that problem before. I discovered it was micro-brushes (brushes that are smaller then 1 unit). At least it was for me, not sure about you though. Try deleting the brush its attached to then remaking it.

It’s brushes that are smaller than one unit in volume.

I think the best thing you can do is select everything and press delete. That brush work is horrendous, you really need to learn how to make brushes properly.

Post your compile log, there’s probably something wrong that’s preventing VBSP from writing a new bsp file, or press Alt+p to see if it’s an Invalid Solid or something

I nicknamed those ghost brushes. Usually it is caused by a solid that isn’t quite right. Delete the brush adjacent to it and remake it.