I am trying to book a SIN-NRT-USA flight. Flights are displayed but all the NH operated flights ( SIN-NRT-LAX ) only show the UA codeshare flight number. Not a really big deal until I would book and try to make seat reservations which now cannot be made on the NH website, but must be called in. Very annoying and time consuming. Only NH flight numbers allow on line seat selection after sign in with NH record locator. Is that something new with UA? Why would they do this? Would a phone call to UA make them change the UA flight number to the NH flight number? A quick check revealed that this is now happening on all flights operated by NH, i.e. NRT to BKK/CGK/HKG etc.