I had created a rather large terrain for the map Above by squideey, and after throwing in a base for it, I decided to add some vehcles.
Now here's the messed up part.
I wrenched it, and set it to an armored van.
Didn't spawn
Set it to chair, and that didn't spawn either.
I'm guessing it has something to do with the environment, but I'm not sure.