When booking a multi-segment trip I cannot choose multiple airlines

[greaper]

I was booking a multi-segment trip and once I chose Delta as the first flight option, the only option available for the remaining segments was Delta even though other airlines would normally be available and were not.  I had to break the trip up into 3 one way flights.  There is also no way to add another flight once a one way flight is added.  This should be allowed in the same way you can add a hotel or car.  This used to work.

[KevinD]

@greaper could you try and replicate this issue and take a screenshot please? That way I can share it internally to see what might be causing this. 

[greaper]

Please see attached screen captures.  In this case I tried to fly from RIC to SEA, then from SEA to MSP and finally MSP to RIC.  For the RIC to SEA trip I chose Southwest.  After doing that, the only airline to choose from for the next segment is Southwest.  There clearly are many other airlines flying from SEA to MSP other than Southwest.  I did no filtering on carriers either.  This replicates each and every time.