Nope, no error code. They display fine. :/
It all goes back to when I copied the save file for back-up purposes. When I booted the game after that some hours later, the notification came up ("The trophy set for this game has failed to initialize. You must exit the game now."). After a few reboots to both the console and the game itself in order to see if it began to work again properly, I went to the save file in question to delete it, in case that was the catalyst. When I pressed "triangle" on the file, it said "Lock: Copying Prohibited" and I remember saying out loud "I'm fucked!".
Why not state this "lock" situation in big, bold letters on the instruction booklet? This is the first game I've encountered that does this, and it fucking sucks.