The site was recently moved from a shared host to a dedicated VPS. Most everything transferred and worked correctly. However when adding images to a new node (Ubercart product to be exact) the thumbnails and alternate sizes of the image are not created. The full scale original upload is visible publicly. In the process of trying to solve this mystery on new images I ran "drush image-flush" and now all the images on the site are broken.
How can I fix this?