My experience: Called and UA's computer showed me as not preferred, even though I was in US's computer. Agent could not put me in E+ because their computer would not let her, so she called US (I gave her the Silver Preferred number, but was puzzled since she can't get in unless SHE was preferred!) and apparently validated I was Preferred. But she still couldn't get in, so she told me she had to take my numbers out of the record and put them back in and it updated. But that only worked for 1 flight so she spent another ten minutes and finally got them all in. It took this agent 30 minutes to give my wife and I E+ seats for the four flights. At that point it felt like such a waste, but it was soo nice on the long flight to Seattle.

Suffice to say sounds like an IT nightmare.