Pay at the pump - Payment amount issue

Today I paid 30.05 at the Tesco pay at fuel pump. Card worked fine. The machine couldn’t give me a receipt but I wasn’t bothered as my MONZO app tells me seconds after I have made a payment. But not today! And when it does appear, there’s only a pound taken, not the £30.05.
I haven’t been with MONZO long but everything has been great up until now.
I have sent an in app query but wondered if others having similar issues.