@AriBarri
Ok. I just did a quick test in my game and it's working fine for me.
So, let's try a reset. You probably already know this but just to be sure, first turn MOO off with bb.moveobjects off. Then turn it back on with bb.moveobjects on. Testingcheats can be either on or off. It's not required to be on for MOO.
Grab an object and press 9 or 0 a few times to see if it goes up or down. Keep in mind that some objects are not affected by the cheat. Others, like most mirrors won't go lower than the preset height. Most can be raised and lowered back to their original height, but you can't make them go lower from that height. So it could be that you're trying to move one of the objects that can't be moved or only moved in one direction.
And it would be helpful to know what object you're trying to raise or lower.
Hope this helps.