Originally Posted by
justmeagain
I suppose I should have made sure that the priority handling tags would be attached to my luggage when checking in with OZ, but wasn't worried since I thought that if they missed it at ICN, CO would have tagged my luggage at NRT. But it didn't happen

Priority tags need to be placed on your bags at the first point of being tagged. OZ failed to do this since they were not aware of your status. CO at NRT would have zero information about your bags "status" since the transfer is handled ramp side.
Lesson learned: make sure your bags get tagged with priority tags
before you walk away from the ticket counter.