This has now bothered me twice with how the world saves to Steam's cloud saving, yet the posters fail to carry with it in the single player worlds. Thanks to both my Patriot SSD failing on me twice I had to experience the posters becoming invisible that you had to find them, guess where they were, and break them. I would love to see them fixed in that they either: A) Have the images save into the world itself that they would carry with the save, or B) Have a slightly greyed out, striked out, N/A notice, or something along those lines to make me aware there's a poster there.
I know where most of my posters are, yet there'll be those few odd ones hiding away. I guess servers have it easier because they have it saved to a folder, yet the single player ones need to have the images saved into the world file, or something like that.