Disclaimer: This could be caused by me using an outdated Steam version, that does not include the new library design.
In the Steam library, the picture showing for the latest reached achievement is only showing a small portion of the actual image; by my estimation 1/16th.
Every other place where achievements are showing (activity feed, achievement screen, layover) does show the correct image.
This is happening since the new three achievements (505, season, books). I do not experience something like that with any other of my games.
As I said, it could either be, that since the last achievements (nov 19) there was another change in the library design, although the Steam interface change dates back further, or maybe you included wrong files for this specific image type.
Anyone else with the same?