Was that from jobs you hadnt completed yet? Because if so, it was probably a reward for finishing a jobgratz on the dn eitherway
I have noticed that, when using wifi, connection speed can alter the drop rate of ec on completed jobs. I spent a week straight unloading on jobs at a place with an extremely slow internet connection. Not a single ec dropped. Whereas, at home i would average 1-2 ec (at the very least) within a day. Idk if anyone else has noticed this inconsistency as well, but it might be worth looking into if you are unble to get a single ec after a couple days of unloading on the "New Party" job.