I was able to talk to an agent at the AA RTW desk this morning who confirmed that the LAN IGU-LIM flight exists and said he didn't know why IGU wasn't there in the online booking tool. He said that no seats on that flight were available for the OneWorld Explorer fare within two weeks of the date I planned to go.

I asked him to confirm/deny if there are EVER seats on that flight available to the OneWorld Explorer and he said he thought there were but I couldn't get a definitive answer.

Perhaps for me this is too much hassle as my start date is not that flexible.

Any other ideas?