I had a problem with OLCI. The nationality shown for my travelling companion was incorrect (CHN when it should be HK) and, if I tried to change it, the "internal error" message would display later in the process. Eventually I decided to leave the nationality unchanged and completed OLCI successfully. Fortunately, this didn't cause any problem at the airport.

As I recall, on the outbound journey they didn't request this information during online check-in. Both airports use the new system (SEC rather than BN on the boarding pass).