Missing Note

[Dovahkriid]

I know I had some trouble finding this one myself. Are you sure you're looking in the right location? IIRC it's in kind of a corner because there's a fence next to the desk. Have you compared the location with a video to confirm that it isn't where it should be?
Have you checked if it maybe fell down somewhere?

If it really isn't there, I suggest you try verifying the game cache via Steam, and then load a save file from the level before where you find it. Then try and see if it appears.

Thanks for the advice. I'm going to try some of these suggestions and report back to you.