it may be because to open my bkk bank statement you need a password maybe that's why they asked I did not question it just gave them what they asked. It took 7 working days for mine and that was including them asking for additional documents
Your recent personal (cash flow / current account )UK/Ireland bank statement shows your name, address, and a minimum closing balance of 11,000 GBP (Screenshots are not accepted).
As I say some of my money goes into my thai bank when I sent them a statement they said want to see funds in my uk account showing uk adrees and no screen shot.
I think it was to show that had funds in the uk with my uk adrees.