I’ve been farming artifacts in an Amigara fault, and noticed that (as per title) after I save my game to the main menu or fully quit, I can no longer access the activated abilities of any of my artifacts. When I try to (a)ctivate one, it says “You cannot do anything interesting with your {itemname}.” It still costs a charge to use, however. They don’t seem to be recharging, either, but I’ve not looked too closely at that. Notably, all their passive effects still work fine.
I did fiddle around in the artifacts.gsav file, and did temporarily mess things up and there were errors when I tried to load a few times. However, I hunted down and fixed those mistakes I made, and never allowed the game to save post-error. So that fiddling around PROBABLY isn’t the cause of this problem, but it might be so I wanted to mention it.