I use a corporate travel agent and if I request an UG before the ticket is issued and the UG clears (I purchase a lot of t-96 tickets) then I get punted back to Y when the ticket is issued... this happened to me several times before I learned to wait until the ticket is issued before requesting an UG... pretty sure it is a travel agent issue (not AA) although I have never pursued why it happens with anyone... YMMV...