Got the message for the first time in a long time...since I flew to India probably a year and a half ago.

Passport is definitely on file and everything. Flying to CGK, with CVG-DEN-NRT on UA, NRT-CGK on NH. CGK does not require a visa, and those who do (at least for tourism) can get Visa on arrival. Not sure if its the destination itself, or the NH segment which is resulting in the issue. I selected a seat for the last flight on the NH site, and UA.com sees that in the reservation. However, at online check in (app and website), it doesn't show a seat on the NH flight, and seat map doesn't pull up. So not sure if that might be the issue. Though weird how the reservation system can see the seat assignment, but not the check in system.