I have installed the lastest version of GSX for sure as I have downloaded it from the website on Monday. Furthermore I have not touched the 777 configuration in the GSX settings, so it's something else.
Just to be sure. You said "the stair used by the crew to board the aircraft seems to be missing".
Are you referring to the front stair ? If you are parked on a parking with a jetway, it's entirely normal no front stair will be there, even if the jetway is docked on the 2nd door but, it has been like this since the very first version of GSX so, this cannot possibly caused by an update.
And, with "missing" you mean you don't see anything, or you don't see the same stairs we used before ? Because, not long ago (but many months ago), we updated the program to not use a passenger stair on cargo planes, but use something more similar to a ladder, because users suggested it seemed wrong to have a full passenger stairs on a cargo plane. But you surely must see either the stair or the ladder.
If you don't see anything, it's either:
- A problem with your plane config, which should be fixed by a RESET, to restore the one that comes with GSX
OR
- Your are parked where there's a jetway (even one you might not see because the Scenery Complexity is too low, but it's there, so GSX sees it)