Originally Posted by
alggag
Either A: It's not 100% live or B: No connections allowed. I cannot find HOU-MBJ even though I can come up with valid connections for HOU-ATL-MBJ.
It looks to be a city specific issue,
where origination must take place in cities that also have nonstop service to the international destination. For example, BWI-ORD/ATL-MBJ is a legal connection because BWI-MBJ on WN exists.
The specific itinerary that you’re attempting to book [HOU-ATL-MBJ] cannot be completed in a single transaction online. Please try again by booking the domestic and international portions of your trip separately, or contact us for further assistance at 1-800-I-FLY-SWA (1-800-435-9792).
It also doesn't help that these flights are mostly in the morning so the majority of incoming flights can't make a connection anyway. Red-eye flights can't come soon enough.