Hello, I think you misread what I wrote. The third poster just does not show up at all on the desk top. It only shows the first two I got. I'll find the third poster and interact with it, but it does not show up on the desk top. As in, there's nothing for me to interact with because it doesn't show that I have three posters. I only have the first two icons, not the third one. That's what I mean by 'not completed'. I cannot progress because it literally does not show the third poster on the desk top.
And yes I know about all the cool stuff on the desk top, that's once of the first things I played around with. It's really cool, isn't it?