I encountered a few TIFF files on Commons that don't get a thumbnail by the software. Their height and width are also identified as 0x0 and their number of pages as 0. When you click on the files however, you see what is expected as any ordinary file. The files are at https://commons.wikimedia.org/wiki/User:Jonteemil/sandbox3. Talk have also taken place at https://commons.wikimedia.org/wiki/User_talk:Fæ#Empty_files.