I've encountered a relatively new problem I'd like to confirm -- UA agents are no longer able to change class-of-service on an existing LH booking unless the full route is available as a new ticket.

My past experience, as well as the opinion of senior agents I've spoken with, has been that the class-of-service for a segment on an LH award can be modified independently of the rest of the reservation. As long as the flight numbers, cities, times, etc do not change, a single segment can be swapped from Business to First (my general use case). I believe I was able to do so as recently as three weeks ago on the outbound for my current vacation (BOS-MUC-FRA-HND, where the two long-hauls had F availability open intermittently).

Over the past week I've tried to do this for our return travel, unsuccessfully. I've worked with multiple agents and escalations, and changing a single segment -- even if it shows availability -- has LH send back "wait list" rather than "confirmed". (I've been able to see this in the booking record as well.) So far I've been able to find alternative, inconvenient routing to work around this (swapping LHR-MUC-BOS to LHR-DUS-MUC-BOS, for example), but this otherwise seems to be a huge devaluation in my award booking options.

Has anyone else encountered this? Any ideas on the cause of the change?