I have a little bit of credit for an unused portion of an entirely domestic trip. I see the PNR under "Future flight credits" on my dashboard, then when I click in to "Use future flight credit," I try to enter an international itinerary (originating in DXB) and it says "We couldn't find an exact match... There are no flights for the selected date."

The same itinerary is available when I search from the home page. In that method, I get a similarly non-informative error when I try to apply the flight credit upon check-out.

I called and, after being on hold for a long time, the agent told me that I can't use this credit for an international itinerary. It's unclear whether this means an itinerary originating internationally or any itinerary with an international component. Has anyone heard of this before? It seems odd and I can't think of a reason for it, other than just a way to increase breakage of the credits on the part of United. The wiki doesn't mention this restriction, nor do I see it listed anywhere on the web page that I searched (granted, I didn't pore through every T&C). HUACA?

(As a test, I tried to book a domestic flight from the "Use future flight credit" link, and got so far as check-out with the credit applied. So it seems that this business rule is applied on the web site, albeit clumsily.)