Well I don't know where it went wrong in the GOF 2.5 scripts, but all the quest attributes for that mission were gone, although the quest log clearly shows they should have been set.
I could not figure out where the flaw in their scripts are, but I was able to reconstruct the missing attributes and saved the game. Save is here:
https://mega.nz/file/bk9k3L6J#J1Zpx9rFZVXigCVAsMJBjN7jpnbbmwAnqDomi54mslM