Happened to me on 2 March, I was returning from HNL. At t-24 I tried to OLCI, same error message, proceed to the airport.... I called the 1K desk, 3 separate times, same thing, can't check in. I was not happy as my RPU had not cleared and I wanted to get checked in and on the UG list. Got tot he airport extra early. Had no problem with the check in. Luckily my UG cleared. The counter agent could not explain why I could not check in prior. She saw no errors out of sync issues.