Two months ago I had a lot of trouble getting a SIN-HND on JL confirmed despite D class being wide open according to both EF and the AA RTW desk. The flight would simply always come back unconfirmed. That DONE had a POC of TYO so I feel like there must be more to the story — it seems unlikely to me that JL would restrict availability for TYO POC as surely that would affect simple TYO-SIN-TYO returns as well?

I remember one of the AA agents telling me explicitly that the flight I wanted to change to was no longer offered on RTWs fares but obviously they could have been mistaken.