I had a similar issue on an open jaw KE ticket from ICN to HKT and BKK to ICN in August. I made the reservation but hadn't ticketed. When I called back I was told that July 21-Aug 21 were blackouts for KE if not originating in the US. Needless to say I was displeased. I had changed a couple of other reservations based upon the understanding that I would be able to ticket this route. The first agent absolutely refused to honor the DL reservation and told me she was going to delete it. I asked to speak with a supervisor, who called KE and was able to get an exception. She did tell me that the exception would not be honored if the ticket was changed.