I've only checked this with a Warshade, but I assume it happens with Peacebringers as well. If you have Nova or Dwarf form selected, and slots placed in any of the "Form Powers", then deselect Nova or Dwarf, all the slots in the form powers vanish. They are not put back into your "Slots Left" pool, and do not go back to the powers they were previously in if you re-select the Shapeshift power that you removed. Neither toggling Level/Dynamic nor Auto-Arranging Slots brings back the missing slots. Saving and reloading does return the missing slots, however.
EDIT: Sorry, posted this in the wrong place. Someone wanna move it for me?
Hm... I see... Thanks for reporting this.