Playing several different games, I found that while I can take screenshots of the game still and can view them in the recent activity for the game(s) I've been taking screenshots in, they wont load up, instead showing mostly "Non-Steam game" on there, and when I do right-click and try to publish a picture from the recent activity section, it says there was an error publishing the picture.

Now, the only thing I can confirm is there is a picture taken still, and the file does exist, going to the proper file directory shows that, but nothing beyond that.