Getting the "This offer has ended" message as well. Also getting stuck on the "Verifying your offer" message after switching browsers.
Found this on the United website: As we keep evolving the digital experience for our travelers, we’ve decided to discontinue the united.com gift registry program. Although you’ll no longer be able to create a new registry or add to your existing one, you can still book travel using the TravelBank balance linked to your current registry until your balance expires.