I got the dreaded ""We were unable to review the latest information for this itinerary" error today. I had booked a multiple destination trip CRP-PVD returning BOS-SAT. Actual Routing was CRP-IAH-EWR-PVD then BOS-IAH-SAT.

I Called the Elite line because, despite selecting seats when booking, was only assigned 12A on CRP-IAH ERJ. Agent said it was a known issue that CO.com reservations with an ARUNK segment (my arrival at BOS from PVD was unknown to CO) cause the error. He deleted the ARUNK segment and I could view the reservation again. Still couldn't get a seat IAH-EWR in A class because apparently only airport assignable bulkheads are available.