Ajani 3 and Knight of Autumn

Magagumo

Using 3rd level of ajani 3's second ability:

Prior to use, I have a Knight of Autumn as first creature in graveyard with one additional copy.

Upon using ability, KoA enters field into third creature slot and triggers to kill a support (noted in battle log). Then nothing else happens. Second KoA still in graveyard and battle log has a creature symbol followed by "Something was destroyed"... Very helpful