Well I have an original Nav Pro from 2013 running hardware H41 and software 0200 and mine does this as well. I have I think got a bit of a work around, however it's weird that it involves not inputting the full post code.
If I am trying to find an address with the standard 7 digit post code - (for example I will use a chip shop in a village near me), If I input it's full post code - in this case - "WA13 0AB", I then get no option to enter a street address. I can only assume the Nav believes the 7 digit code is near enough to a small area to be able to find your address ?
However, If I enter only the first part of the code e.g. "WA13 0", I can then press the list button which gives me the towns under this post code (usually only one or two), then then is a list for street names to select from (again usually only very small), then you can select a street number. Obviously this is useless if all you have is the full post code and not the street name.
Like I say, it sort of defeats the point of a full 7 digit look up, but as I say, I can only assume the 7 digit area is quite small. This is what Wikipedia says about the last 2 digits that make up a 7 digit post code (called post code units)
"The postcode unit is two characters added to the end of the postcode sector. Each postcode unit generally represents a street, part of a street, a single address, a group of properties, a single property, a sub-section of the property, an individual organisation or (for instance Driver and Vehicle Licensing Agency) a subsection of the organisation. The level of discrimination is often based on the amount of mail received by the premises or business. Examples of postcode units include "SW1W 0NY", "PO16 7GZ", "GU16 7HF", or "L1 8JQ"
