Why does UDU request dissapear after a simple change?
 

This is something that drives me nuts. On many ocassions, when I call United to make a simple change to a reservation (e.g. change flight from morning to afternoon) the status of the upgrade (UDU) request changes from PENDING to nothing. It just dissapears.

Why is this?

Because UA's IT monkeys who wrote their back end (too bad there are only a finite number of them) are basically Junior High School dropouts.

Poorly designed software. In these cases you have to get the upgrade added manually.

This did happen several times to me as well when my reservations got changed either by my call or due to schedule/aircraft change. I lost several UDUs for this.
It is good for you to pay attention to this .bomb problem.

Thanks. I just called and had them added again. What a PITA this is though.

Used to be that you could re-add it yourself by going to the website and requesting an upgrade with E-500's, however they seem to have finally removed the E500 option from the list, so even that's not possible now and the only option is to call.

I had the same problem this morning, and I made the change online. Maybe it would have corrected itself with time, but I didn't want to take any chances so I called.

I'm sure you'll enjoy the future then. When I made a change to a CO flight online, the other flight on the itinerary lost the upgrade-for-miles. I was back in economy, and the miles were still gone.

This is the system that UA is going to switch over to.

The true answer is UA has no clue, they think it's either the idiot programmers or the idiot executives. Regardless, the Executives run the show and they will blame it on the IT guys...so now if you thought the IT services were bad, you'll really know what bad is. Thanks again for giving your money to the executives at UA...they don't appreciate it, but it does go into their pockets.