I don't know if it's a bug or intentional, but the famous bar pretty much stops filling when you are somewhat 90% done. The fact that noone got that medal (except Shadman before the game was even published) kind of seems to prove that its intentional :(
It's just frustrating a medal exists, but you know you'll never be able to get it. Just like the artist in the game is doomed to get depressed and kill himself.