Mamayev - Axis Engineer - Lose points for blowing up objectives

As per the title, on Mamayev Kurgan as Axis Engineer I've been finding over the weekend that when I satchel an objective, I get a -5 team points penalty rather than the expected +5 points.



And before anyone asks, no I've definitely not accidently TK'd someone as I retested it on an empty server.



I've not done a repair yet, but this is surely a server side problem as it's to do with scoring right?