API developer account Payment failed Inquiry

I am a ChatGPT API developer and have been paying for API bills for months.

Recently, I have got an email saying I have a overdue invoice payment for my API usage, which I am quite suprised about it. Because I overpaid the bill last month, which I topped up $100 for paid off a couple of dollars at 16th Jan 2024. But today the system told me I have an invoice payment failed and my using API will be interrupted.

My understanding is the $100 top up should make my account to have enough balance to paid off the following months invoice, but still got the email saying it the payment failed.

Should I be worreid about it? Or how can paid it off by my current balance credit?

Thanks a lot!