Originally Posted by
Duck1981
Great advice - thank you. Chatted via WebChat, the issue was that I did not know that I need to input the letter before the passport number in the system (I normally never deal with
Austrian passports).

Must be an older one with a space between the letter and numbers? Is the letter a P by any chance? I too had assumed it was just meant to denote the number was passport but the letter does show up in the MRZ. The space has gone with newer-issued ones (just checked my wife's passport issued late last year) so presumably the Austrian government figured out there was an ambiguity.