Hi richard96 When you view the invoice via the print and preview section and select the print icon in the top right hand corner of the black area, please hover your mouse in this area, does the sort code show at the bottom of the image. Also, if you download the invoice and attempt to print it are you still experiencing the same issue?
The problem was I had already created the invoice, then edited the master style to make a new custom invoice template. I went back in to the invoice and applied the new template to the invoice using the 'customize' option at the bottom of the screen. When you do that, it picks up most of the new template, but it doesn't pick up the 'message to customer' field.
But it works fine when creating new invoices going forwards. So I deleted the invoice and re-created it from scratch. The 'message to customer' field is then populated correctly, so all working fine now!