I can’t speak to this form, but in the past I have had validation issues with my actual postal code (X1X 1Y6) vs the way it was formatted. When I moved into my building it was new, and a number of address validation databases (even 18-24 months in) did not have my postal code in their database.

In the end I used the generic postal code for the street (X1X 1Y4) which was in the database. My Nexus and EZPass accounts are both databases that had this issue.