@JTT The central point your referenced is a watchtower and not a drilling site. The 3rd site is further west of the other two you circled in this screenshot.
That said, the mission does highlight the three pick-up sites but you can complete this mission just by visiting the same pick-up point if desired. A bit of extra challenge would be forcing you to visit all three locations to complete this contract.
Ups, sorry. But I am quite sure, "it vanished". Maybe. And by picking up three containers from three sites I assume, that was the idea behind that mission.
At least I managed to roll over my "White Western" three times at three different locations and managed also to put the container back with my 2070A and a yellow crane....