As Marion notes, we haven't been able to reproduce this problem, either locally, or connecting to the AU servers with an AU install, so whatever help we can get to find a reproducible case would help us find and fix this as soon as possible.
I've updated the tickets with this information; please update the tickets with this information (though feel free to post here, as well). For folks that are having a problem purchasing User Content that they have approved, please do file a ticket with this information.
Post the full path of your My Documents > Pirates of the Burning Sea > userContent directory.
Provide the count, names, and file sizes of any files in the userContent cache currently.
Go to your Nation’s starter town, to the Flags and Sails Customizer, and check for flags and sails; take a screenshot of the Shop window when it’s open (use the in-game mechanism by pressing ‘P’, as well as using the Windows mechanism with Print Screen), then quit and exit the game again.
Provide the count, names, and file sizes of any files in the userContent cache currently.
Check that the screenshot you took in-game appears in the My Documents > Pirates of the Burning Sea > screenshots directory.
Did you have the Station version of the game installed before installing the Bigpond version? If so, did you remove it entirely before installing the Bigpond version? If not, are the Bigpond and Station versions completely separate (except for the My Documents > Pirates of the Burning Sea) from each other?
Thanks for your patience and help!