They have done some updates so that now .tiff, .jpg, .png and maybe other image files (I only tested those three) now auto-generate their thumbnails. The current instructions to update ImageMagick are here. Unfortunately PDF thumbnails still aren’t being created. @sunyue also posted about this ongoing problem over here.
Considering PDFs constitute the most common file uploaded to our repository this has been causing some workflow issues. I remain optimistic that Reclaim Hosting is working on a solution for this.