Destroyer rewards for pvp battles

Ive done the broker mission to kill destroyers in PVP it says it gives 15 neodium for reward ,I have done 2 days in a row now and only got 8 each day is this a bug or is there a reason Im only getting 8?? thanx 

You should be getting 10 on one day and 15 on another day. That’s probably why you think your only getting 8.