If a torrent download is renamed and the rename changes the file type, the icon is not updated in the main window.

For example, if I was downloading a file called MySharedPicture.doc, it would show a Word file icon. Now let's say it is actually a PNG file, so I rename it in Transmission to MySharedPicture.png and the icon in Transmission will stay a Word document (at least until the next time Transmission is run). Note also that QuickLook does handle the file correctly, just the icon is wrong.

Running macOS 10.12.