More people feed in there cages than feed in a separate container here. It won't make them aggressive.

Many of use believe its a good way to get bit. Your moving your snake while it is in feed mode and possibly with the scent of rodent on you. This also causes them stress by removing them from their home to a bare container and then expect them to eat.

I would suggest trying to feed your problem eater in its home and see if you have better luck.