The whirlpool in door ice uses an optics system to detect a full bin. When the ice piles up to the u shaped notches at the top of the bin the optics sight gets blocked telling the control board to stop cycling the ice maker. If the ice is overflowing the bin it would indicate the optics board has failed.
When did the optic system began being used? Within the last 7 years or so? Shows how out of the loop I am. I'm sure there are a lot things on the newer appliances that I would be completely unfamiliar with.
I bought some new ones within the past year and dread when they start messing up.