Ziggurat - final boss bug

This is the second map in a row that this has happened to me. For some reason 2 of the minibosses spawn at the same time, then I phase the boss one more time but because there are no minibosses to spawn, they are stuck in their invulnerable state. Bug report 437,420,077. And bug report 3,358,735,285 for the first time it happened to me.