I can upon a odd instance while trying to edit the thumbnail in my file manager in my 5.7 installation.. This may be the way it was designed (though it seems a bit counter-intuitive) but when you finish editing a thumbnail from an image's "properties" there is no save button once you return to the 'edit thumbnails" page. Not only is there no save button but there's no way to tell you even made any edits unless you close all the windows an completely refresh the "/files/search" page.. So to any unaware user it seems as though the edits made to thumbnails are simply not saving. I spent more time than necessary bug searching and wondering why the preview did not update my new thumbnail specifications. It wasn't until i flushed my cache and reloaded the page did i see my thumbnails update, and upon further investigation i found i simply needed to close the file editor an refresh the page to see my changes... IJS seems like there should be a save button on the initial thumbnails preview page or an automatic refresh to save confusion an headaches.