I've been looking now for an hour... I cannot seem to find it.
There is a command that allows for editing the actual line work in an object controlled by the Display System... it is a last resort command if you cannot get the object to display as you wish.
What is it?
Don't know but does the object have an object override? That's caught me quite a few times.
Have you looked at the 2nd tab 'Display' on the properties pallete?
I've attached a simple lisp program that will lock every viewport in the drawing and change the layer to Defpoints. You possibly don't want to do that but if you do you can open and alter the layer you want them on. Also the colour of defpoints layer is adjusted. putting a ; in front of that line will stop that from happening.