I had that feeling during the previous round already, that despite hitting hundreds of regular guards in the first phase, I hardly ran into SEGs during phase two. Supposedly, killbeating regular guards increases the spawnrate, but I still ended up elixering away a ton of regular guards to get to the SEGs.
Maybe they lowered the spawnrate, maybe it's just RNG. Ah well. As long as I reach 100 SEGs, I'm fine.