Character/Object Centre point

On a few occasions some of my object center points get ignored by the characters and the scene isn't layered correctly, If this starts to occur, the only fix for it seems to be to use the icon 'Sort objects by object centre', which seems to fix the bug (Until it occurs again).
VS4.2

The objects have to ordered correctly according to their object center values. It's not a bug per say, it's just how the engine works. It's advisable to manually set the object center for each object & to press the sort icon in the toolbar after adding or removing any new objects just before saving & running your game.

If the objects are not ordered correctly then you can end up with some strange side effects such as part of character sprite being masked out, or certain objects always being on top of everything else etc.

Ok, so setting the centre values is not enough on it's own, the list has to be ordered correctly too.
Thanks.