I'm GS flying a B fare on a trip in 2 days with C9 inventory, and my SWU is still waitlisted. This was the response I received yesterday when I asked them to pre-clear the upgrade (in the past, they'd always done it for me):
Hello ajc1970,
The issue is that we have several 777 aircraft in service now, especially to LHR, that have completed the refurbishing of the interiors. The problem is that we don't know the routes they will be flown until very close to the departure. Because there are fewer seats in the upper cabins we are trying to minimize downgrading anyone should the new interior be used so upgrades are being held back, pretty much until check-in. We would rather have good news at the departure that we can upgrade someone rather than disappoint our guests if we have to downgrade their cabin if we don't have enough space for them.
Specifically for your flight on Thursday, if I had to guess, I would say it looks promising for you.
We regret this inconvenience but to be totally truthful with you, it's going to be this way for some time while more 777 planes go through the modifications.
Best regards,
name withheld
United Global Services
Product Specialist