We had RUC's applied when we purchased the tickets. They were originally issued with a standard 006 ticket number but they were reissued when the RUC's were applied. The reissued tickets are a different number (as expected) but they also have a hyphen and a 2 digit number after the standard ticket number. That's probably why the check-in process can't handle them.

We're not flying that trip until December but I'll stay on top of it thanks to your info.