Endless Mode isn't endless...
Endless Mode on Mendel Covey (sorry, wrong map).
It's a bit annoying to play perfectly for 45 minutes, and then there are no more waves. And you're stuck ingame with nothing to kill, and have to do a surrender.
It's happened twice in a row now, which indicates to me that this is a permanent bug, and not just something that happens once in a while. I think I it was 87 waves total.