I’m only posting to confirm a common bug I encounter during enemy specific rounds such as kill 100 Crawlers, that is if you kill the Crawlers off spawn or too fast they stop spawning.
Yes, that can happen. I’ve had that happen to me on two separate occasions during protect the Forerunner core rounds.
Sometimes enemies decide to stop spawning, but I don’t think that glitch is limited to enemy-specific rounds.
Ive seen it a couple times. Super annoying to lose a match on the 1st round because of this 
It’s very annoying to lose on the first round and almost as - but not quite annoying as defensive rounds. That’s a pretty big glitch to give everyone an L while they sit there and can’t do anything about it.
It’s pretty fortunate to get the glitch on defense rounds since you basically win for doing nothing. Having to wait for the entire round to end is annoying though.
This happens to be a lot on the Temple.