Is the drive with the free 1.6TB your C: drive?
Yes, it is the C drive. It seems to be the same for AlexB.
I'm not saying you are wrong about the 1.6TB but have you checked how much free space you have since the patch? Clutching at straws here but maybe the update somehow managed to eat your free space (1.6TB is a lot of eating though). Another thing to check would be how big your save file folder. (I've not updated but for reference my entire Larian Studios folder is 5.98GB (the saves are about half of that)).
