So I now have both my PMDG planes and GSX loading again.
I re-ran the FSDT Live Update but "not" the FSDT Installer so it completed and silently exited.
Re-Loaded MSFS and both the PMDG planes and GSX are there and loading.
Despite this there is no PMDG "integration" Called the jetway which worked, requested boarding and started getting notifications to open Cargo doors and the crew walked through entry 2 rather than open it first...
Next step would be to go back into FSDT Installer and "configure" GSX for seated passengers in the 777 and see if it repeats this entire process again and improves the door integration and seated passengers or starts the uninstall-re-install process again.
Edit: Went into FSDT Installer and used the Configure option to re-enable 777 Seated Passengers. On the bright side, nothing was removed or deleted this time. I did only enable 1 plane at a time however so I have NOT enabled the 737 800 Seated passengers option yet. I did not want to make too many changes at once.
Edit 2: Re-Ran FSDT Installer and enabled 737 800 seated passengers. Again, no disappearing planes this time and GSX is functioning however similar to the 777 using the PMDG ofiicial United livery passengers board, turn right (although at least they use the aisle not throug the galley) and then disappear.
So neither the 737 or 777 with PMDG official United liveries are working. MS Store editiion. Also, my Community folder location is non-standard. It is M:/MSFS/Community if that is relevant.
So now at least I am back where I started with the 777 and GSX loaded using the United Evo Blue livery (PMDG official via Ops Center) but there is no door control, crew and passengers board as though it is a single aisle aircraft getting on the plane turning in the middle of the galley towards the cabin and then disappearing into the galley.