I have the same problem like SquadronLeader.
But always after installation of the Update, nothing is happening. I have still the old Version of the b777.
Also everytime when I opened the Operation Centre again after this, I have the same notification. The same update like 1 minute ago.
For me it is no issue to use the 777 200 LR/F version of it, but I cant Install the 300ER expansion pack for fsx.
Also when i try to open the Operation centre in the administrator mode, i recieve the message, that the "PMDG_Updater_77L_XSE.exe" isnt found. I have no clue how i could fix the problem.