movie thumbnail jpegs not all recognized

I have recently installed Serviio on my server, and wish to use it as a movie server for my several WDTV HD Live boxes. I have a few 2TB+ USB drives full of movies (my ripped dvd collection) that I wish to be able to access. I plugged one drive in and loaded it into Serviio library.
The drive contains about 350 movies, each with a DVD cover jpg all in the same folder (movie-1.mkv, movie-1.jpg, movie-2.mkv, movie-2.jpg, etc.). Serviio is set to "Look for local DVD cover image or poster" only ("generate thumbnails" and "retrieve DVD cover if available" are both disabled.
My issue is that my WDTV boxes can browse the folder, but only the first 98-100 movies are thumbnailed with their correct posters. All the rest have been assigned the folder.jpg icon (used by WDTV as the folder icon). I have removed and re-added the drive to the library, uninstalled and reinstalled Serviio, waitied several hours for the library to maybe finish updating the thumbnails, but nothing seems to help. It always stops recognizing the thumbnails at the same movie and goes no further even though the format is identical on all files. This is the same on the subfolder, which has about 15 movies, but only the first 4 recognize their thumbnails, and the rest again get assigned the folder.jpg image.
Any thoughts on how to get this to properly recognize all the movie.jpg images? I have to plans to let Serviio download the metadata, i only wish it to recognize the pictures i have already downloaded.
Thanks very much for you help. This software looks very useful and I will purchase the Pro version (for wireless streaming to ipad) if I can get it to work with my thumbnails, which I consider important for the look and feel of my setup.
The drive contains about 350 movies, each with a DVD cover jpg all in the same folder (movie-1.mkv, movie-1.jpg, movie-2.mkv, movie-2.jpg, etc.). Serviio is set to "Look for local DVD cover image or poster" only ("generate thumbnails" and "retrieve DVD cover if available" are both disabled.
My issue is that my WDTV boxes can browse the folder, but only the first 98-100 movies are thumbnailed with their correct posters. All the rest have been assigned the folder.jpg icon (used by WDTV as the folder icon). I have removed and re-added the drive to the library, uninstalled and reinstalled Serviio, waitied several hours for the library to maybe finish updating the thumbnails, but nothing seems to help. It always stops recognizing the thumbnails at the same movie and goes no further even though the format is identical on all files. This is the same on the subfolder, which has about 15 movies, but only the first 4 recognize their thumbnails, and the rest again get assigned the folder.jpg image.
Any thoughts on how to get this to properly recognize all the movie.jpg images? I have to plans to let Serviio download the metadata, i only wish it to recognize the pictures i have already downloaded.
Thanks very much for you help. This software looks very useful and I will purchase the Pro version (for wireless streaming to ipad) if I can get it to work with my thumbnails, which I consider important for the look and feel of my setup.