Eater of Worlds altars in Mirage Elder map

I have been running Elder/Shaper/Conq/Memory Guardian maps for the Gallant Grinding Goals Challenge, and I noticed something. The mobs are offering Boss alter choices when it's either dead, or not in the Mirage. Not sure if it has to do with the interaction of him being sucked up by Elder and it's giving a "false positive" or not.

Bug report # in game: 512,958,980


Hope this helps, and thanks!