I've managed to recreate the CP/Forum categories bug. Basically when you have several categories nicely arranged 1, 2, 3, 4 etc and make a new category it becomes 0. So if you want it to put in place of 3 for example you change 0 to 3, 3 to 4, 4 to 5 and so on - submit . After submit you end up with all sorts of stuff, some numbers even duplicated. In order to make it work properly you have to do it 1 at a time. First make space for new category by rearranging the old - submit - then put the new category in the free space - submit.
