Fatal Bug which stuck the playthrough

the elite creature which supposed to carry the ‘Water Channel Key’ doesn’t spawn, making the playthrough literally impossible.
here’s the log files + save files + dxdiag + videoclip

also there’s more than one player who suffer this trouble which makes the save totally unplayable.
steam community on this bug

It’s a 17Hr savefile-at least make the save patched please. It’s really devastating.