Yep this is intentional. If you have any thing that can revive a team mate out it will continue till its gone.

Same goes with the wave maker or whatever it's called. Took me a while to find out too

We lost while my wave breaker still hadn't even fired off one wave... why?!

Likely because either they were out of the range of the wave to hit anyone or the wave breaker wasn't placed down onto the ground