For some reason, my Wakaba installation has decided to stop linking thumbnails to the database, or something. Basically, when an image is posted, a thumbnail is generated and placed in the thumb directory, as expected. However, it doesn't display on the board, and instead only shows the "No thumbnail" text. When I do an SQL dump, I notice that the field for where the thumbnail file name would be is simply blank for each entry.

I am using shared hosting (Lithium Hosting), and I really don't know what kind of thumbnailing software they have installed. It's simply worked up until now. With that in mind, anyone know why this would be happening?