When i start kontact or kaddressbook "standalone", the category filter always is preset to something that does not even exist as a category in my address book, therefor making the list of addresses appear empty.

Workaround: click the "clear category filter" button, which sets the filter to "All".

It seems that the list of categories got populated from the categories in my CALENDAR, it contains a lot og categories that I used in calendar entries, but never for addresses....