I had a similar incident in DXB on my last trip where I had a wait of almost 6 hours and noticed in BOM itself that the seat for my onward connection from DXB had gone to None. I went up to the F lounge attendant at DXB and requested for a new BP. They just commented that they couldn't view my seat. I waited for an hour and then as the shift changed, went up again to request a new BP. Again, they said that they couldn't view my new seat. Fortunately, when I went up to the gate I got an upgrade.

So my sense it that there might be a situation where they might have put you on a list for an op-up but not actually assigned you a seat in J, until last minute. Just a theory....