UA in general has stopped offering itins with no UA operated flight, codeshares or JV flights, Asia, Europe, ...
This has gradually been occurring for years and accelerated with "no change fee" decision.
The IATA also passed a resolution discouraging plating / ticketing flights without a carrier operated flight.
Additionally, many partners have instituted plating restrictions that effectively blocks many routes / fares UA used to offer.

These actions related to cash tickets, award tickets have not been effected