Hard to say without more info, hmm. So it's just not even showing the saves in the "load game" dialog's list? If that's the case, that probably means something wrong with the descriptor.xml files, but, again, hard to say for sure without seeing them.
Could you send me a save so I can check it out?
Also, if your save list is long, and the game thinks the saves don't match the current set of enabled mods (which, you did say you didn't change), then the saves will be at the bottom of the list. Just throwing this out as something to double-check.