If anything is spawning then you are doing it much too slowly. Although I've done gally and non gally methods, the gally one goes like this, for us... All three w 7 in chamber and a synth ready. Run out w two running to the left side and one hanging back. Two kill survivtor, pop blessing, and start hitting him, while third is in the arena outside of the door into the arena hitting him from the backside. Unload all, go back into bubble, pop synth, then continue unloading until mine time. The guy in the arena acts as a teleport balance so skolas doesn't move up onto the left platform w the other two.