City Square bosses bugged in mirage area when only 1 is in the zone

If the mirage in the City Square only catches 1 of the 3 bosses the area still recognises a boss in the zone. The zone information notes 1 monster remaining, eldritch alters will offer map boss boons, and the boss will even have the mirage specific boss effects/attacks trigger from it. However the boss is completely untargetable and has no health bar, it also does not move or attack for itself.

This issue does not occur if the mirage catches 2/3 or 3/3 of the bosses, it only affects it when it's 1/3, although this issue does happen quite frequently on this map.