enemis not spawing corectly in sanctuary onslaught

[aspeedninja]

im not sure if its just me at the start of the round where where plenty of enemis spawning, but later in the wave it just seemed the spawning when down significantly and u could also see when i used sonar there where almost no enemis on the map, and i dont think it was because we killed them so fast, but i could be wrong, but it just loooked like they where not spawning in