Welcome to the Community, @Plusfactor. I'll help you out with this issue about finding a statement number without a customer name.
I suggest reaching out to your bank where the bank statement came from. This way, they can help you pull up the information you need.
Moreover, keep this for future reference: create and send customer statements. It has the steps you can take on how to send statements to show customers summaries of their invoices, payments, credits, and balances in QuickBooks Online.
Stay in touch if you have any other questions or concerns. I’ll be right here to answer them for you. Enjoy the rest of the day.