Laboratory Boss spawn with Scourge

I was doing a Redeemer on that hit Laboratory Map. When I was opening the middle lever(after having opened the 4 levers) I was in Scourge, and the mobs you need to kill to get to the boss room therefore never showed up.

I tried clearing all mobs, and making sure I had clicked on all levers, but the mobs you need to kills to open the last portal never showed up, so couldn't complete the map.

There seems to be some sort of bug with levers while Scourge is ongoing.

same thing happened to be lost my drox cause of this