Both the save and Quicksave options are grayed out. It doesn't matter what part of the game I'm on, it won't let me save. Auto save doesn't appear to be working either. Anyone else having these issues?

Yeah, though a bit different. My save and quicksave are selectable but then I get a message saying there isn't enough space, when really I have over 122 GB

I'm having that same problem myself and i have 300GB free space

I uninstalled and reinstalled the game and that seems to have fixed the problem for me.