The DR form below contains an image upload field. The image type is set to Display Thumbnail and the thumbnail type is set to Relative with a height of 100px (the width is blank). When an image file is selected and the preview link pressed, a correct thumbnail is created and displayed. However, when the submit link is click and the form is re-displayed, the thumbnail is not displayed. If the image type is changed to Display Full Image, then I see the full sized image. Based on testing on my system, I could see that the thumbnail image was not being created when the submit link was clicked. Thus, there is no thumbnail to display.