First off let me say this was a fix when using my WDTV Live with My Book World Edition II - 4 TB. I have had the media server set up for a couple months now and for the life of me could not get thumbnails to show. Yesterday I found a post on Twonky ( http://www.twonkyforum.com/viewtopic.php?f=2&t=7121&p=27045&hilit=thumbnails#p26402) and it worked for me.
The folder.jpg has to be named:
Folder.jpg (with the F capitalized)
The moment I renamed and rebuilt the Twonky database all thumbnails showed up. Maybe this will work using network shares…I am not sure. But I do know I can see all my thumbnails using network shares and Media Server views.
I should also state I updated the xml on the media server as well. But I did this a long time ago and I am honestly not sure if this helped. ( http://wdtvforum.com/main/index.php?PHPSESSID=d4857d760341f9510fc094e15f8ec107&topic=3126.msg25780#msg25780)
All I know is when I changed the f to F then the thumbnails all appeared.
Thought I should share. I could not find this info anywhere on this message board…so if it is here…and I missed it…sorry about the post.