I added a cube and a cylinder. When i now substract the cube from the cylinder using a Boolean Modifier it looks like this:
Like the cylinder has just a shell and no volume.
I checked the normals i checked if there are any missing faces (what shouldnt be possible cause i just added the cube...but in case) There are no other modifiers on them. I added another cube in the exact same location and subtracted it with the same boolean...and this one works. i just wann know...