To add onto this, on Whitechapel you can grab a carriable from the church during the 1st phase of offense and run to the area that the EV would be “stopped at” (facing down the hill towards the next objective) and actually deliver the objective.
Then once the EV is in position the EV Ammo will respawn in the chapel and will be very hard to grab. Very hard meaning it can take 20 tries, or it can take over 100 tries to actually grab it. Once it has been grabbed it can be delivered no problem and the map will progress to the next stage.
This was experienced on US Stopwatch 01 at around 10pm CST.