All of a sudden (at some point in the last 10 minutes), when I load a save off the server (my own or somebody else's) the decoration layer is not loaded. It still appears in the preview in the game and on the web site. I tried restarting TPT but it did not fix the problem.

Thanks! Nope. I tried turning the layer off and on a few times, and entering and exiting the editor a few times too. The "D" layer button in the top right shows that the layer is on.