Bank won't accept scanned passport


I live in the UK and I need to close a US bank account. To do so, I have to send a scan of my US passport via a link the bank provides. I’m only allowed 5 tries. I’ve photographed it on my phone and done scans from two different scanners; three of the 5 tries have been rejected. I’m wondering if the fact that it’s a biometric passport has something to do with it. Any suggestions?