Can't check availability or fares for MEX-MAD or MEX-BCN; I get the "Continental.com could not find any available Economy seats meeting your requirements. You may modify your search criteria, or call 1-800-300-1547 for assistance." message. However, searching separately for both the MEX-EWR and EWR-MAD/BCN availability does show up.

No problem searching for other destinations.

Searching for reward travel on the same routes works correctly, though.

Also, when it's a flight number with a scheduled change of aircraft (CO63 MAD-EWR-IAH, for instance) the seat map for the second segment does not show up.