Hello folks, I wonder if you could help me with your vast experience of this...

Never flown UA before, but I have a BD award on tomorrow's UA929 LHR-ORD. Am *G, so have nabbed 17A and 17B on the 777.

But... Online check-in is failing, with no specific reason given. The flight, looking on KVS, is booked out, with a single C seat showing.

With the overbooking, and BD's habit of getting award bookings disastrously wrong, is there anything I should be concerned about? Or is this par for the course for such a routing/ticket/overbooking?