Only 1 yen charge to Youtrip for petrol in Hokkaido

Hi everyone! Recently I’ve been to Hokkaido on a road trip and it is my first time renting a car for my vacation. After using a Youtrip card to pay for petrol at one of the gas station (ENEOS) I was surprised to see that I was charged only 1 yen after the attendant has charged my card despite the receipt stating that I had loaded about 2000 yen worth of gas. Does anyone have any similar experiences?