Just before the last drop off point to get into the finale event arena with the explosive barrels if you dont rush into the area because of something happening then players/bots will always respawn after the finale event, this happens before you have even jumped down to start the finale event.
I have been in situations many times where i either had no help at all for the entire finale event or only had 1-2 players/bots helping because of how buggy that part of the map is with respawn locations.
This bug report is extremely similar to my count mordreks fortress bug report but its on a different map.