Tried it and seems to work. Most times I run my level from SED and not WED though.

If you load the level from a script and have added this script to your level via map properties you can remove the "level.wmb" in WED engine options window, because it give different result. If not sure, you can remove the whole line in WED engine options window and press OK button.

So in other words: world.c -nx 30 world.wmb

becomes world.c -nx 30