Have you changed the location of where you originally installed the games? Moved them to a different hard drive? Geforce experience cannot optimise them if it cannot find them.
Have you launched some of the games before you try to optimise them? Sometimes you have to do an initial launch then go back in to Geforce experience.
Also, just a thought, don't have too much faith in the optimised settings, I've noticed that on some games (GTA V, in my experience) it really overestimates how well the game will run and in others it sets the settings way lower than you would expect. Always have a play around in the graphics settings, you can usually get it to run a little better yourself.