I had some WX 1200 access points (you know, the ones that came for free with an NBX) running the factory firmware, that could not be connected to when using a normal wifi passphrase (non-hex). The fix was to enter the hex passphrase using a passphrase generator such as this one:
http://jorisvr.nl/wpapsk.html
I can't remember the specific firmware and the APs are offline, but suffice so say they didn't work without this.