Alaska Airlines tells me that if I want to add an intra-Japan segment to my award ticket, they need to have availability from origin to destination. So to add a segment to my existing business class booking I would be better off redeeming 12.5k miles for the new segment on a separate reservation. Is this true, and if so, how long has this restriction existed?
I have had this exact problem with award travel on Fiji Airways, so does it happen with all partners?
Edit: I decided to book the extra segment using 10500 Avios plus $0 rather than 12500 Alaska miles plus partner fee. I can get all the Avios I need from Capital One points. Alaska miles are harder to obtain since the long ago days of Marriott Vacation Packages and redepositing the hotel awards. That was fun.
If true, would be a new restriction. I called like two weeks ago to add on PEK-HND to a HND-USA JL J booking for free. There was no J availability on the tpac segment at the time I made the change.