Yep, had it happen at the Duergar camp. No matter what I do, whether I walk in and try talking to them, or sneak in and assassinate them, the MOMENT I start interaction with Duergar I am no longer able to Save or Save As. I had previously reloaded a save just before Duergar camp and went off to visit 'immobiles' and the 'floaty thing' and then went back. Moment I started interacting with duergar then Save was stopped again. Game has to be restarted to reload any saves that allow Saves.
I see that others have this issue with other scenarios so it's just luck of the draw I guess.
Will reload a previous save and skip the entire Duergar storyline. Plenty more to do so that's cool.
Good luck Larian!
And any Devs releasing to early-access have to have thick skin - but 'EARLY-ACCESS' is early access. No reason to get heated over issues. In every case, the moe detail that surround th issue the better and more chance it can get sorted out. Thanks in advance!
FINALLY finished the Duergar mission and still able to save, Only way I could was to 'glitch' it by sending (Spoiler)
On ending, can still save and scenario goals achieved.