Sorry for the bump, but this is the first result for “no thumbnail” and I thought I’d add what fixed this for me. After a fresh install of the newest version, I was having this thumbnail issue. I tried the inline-updloading hack, but that didn’t fix it for me. I poked around the code and found the thumbnail making function (wp_create_thumbnail). Before it attempts to create thumbnails, it verifies that you have the required php functions available (imagegif, imagejpeg, etc). If you don’t, it’ll fail silently. All I had to do was enable these functions in PHP by uncommenting the “extension=php_gd2.dll” line in my php.ini. I tried an image upload again and, voila, thumbnails!
