Back to basics!!! What fuel load did it arrive with on board and how much did they put on. Now that can't be hard, or can it?
Did I miss something? That's what they were concerned with, hence dripping the tanks. It was the dripping that wasn't done correctly. I sympathize with the crew if they were told 86 T onboard after the check.
There was an Air France A319 that ran one tank dry despite it showing over 1000 kg remaining. Google it!
Funny little things those indication systems.