I have a similar problem with a segment not being credited to me. I flew MCO-ORD-PVD a couple of months ago, but was crediting to US. MCO-ORD posted, ORD-PVD did not. I sent boarding pass and e-ticket documentation to US Dividend Miles service center. United is insisting I "voluntarily offloaded" at ORD and did not fly ORD-PVD. But I did fly that flight in my assigned seat. I even checked a bag through at MCO and retrieved it after I deplaned in PVD.

Unfortunately, these miles are making the difference between US Silver and Gold status. (I'm trying to decide if it's worth it to do a last minute PVD-PHL roundtrip one day before the end of the year, but I want to make sure this is really a lost cause before I spend the money to book that.)

Any ideas?