Boolean Modifier acts like the object has no volume 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...

please halp
I noticed the scale of the two objects are different so I'm assuming you scaled one of them.

If you resized the cube or cylinder try using 'apply object transform' and mark the scale and rotation. Probably even if you see the object as smaller or bigger, Blender doesn't take into account that the object has a new volume.

Most of the times it will fix things so that afterwards you can successfully apply the Boolean modifier.