Why the payment is not calculated properly in the form?

We have created a nomination form for an upcoming volleyball tournament.

We have used the "Calculator" field to autofill the Stripe payment gateway with the correct amount.

For some reason, despite appearing to work correctly when we complete the form, a submission without payment has been received.

Note, payment for this form is a compulsory field, as are the fields that determine the payment amount.

Attached is a screenshot of the submissions, the top submission is the faulty submission with no payment. This was received at 12:50pm. An hour earlier, at 11:45am, another submission as received (that would have calculated the same amount) and the payment was correctly calculated.

No one has altered this form during this time period.

Can you please explain why this error has occurred?

I checked the last submission, and I see it is showing zero for payment calculation.

The fields are filled properly in that submission:

But yet, the calculation is wrong. I assume this could be a glitch that occurred since the information from Browser is not picked up either:

Do you have any information about the submitter, like from which Browser did they submit?

Thank you!