I had that problem when I tried to add the 2 cups of flour to the mix that had sat overnight in the refrigerator. Doesn't help that the Kitchenaid "splash guard" is a worthless POS, they should do better for the price of those mixers. I ended up taking the bowl off the mixer and used my hands to get the extra flour incorporated.This time I kneaded it in the Kitchen Aid, I’m not sure it saved any time considering it shot flour all over me and the countertop