If selecting a "JMFilePicker Upload File" field to display in the item overview
in the LISE Instance option, the thumbnail does not display.

If having uploadet a file to a path like "uploads/images/myfolder/foo.jpg"

The filename the image tag is looking for is "thumb_images-myfolder_foo.jpg" but
the actual filename generated by JMFilePicker is "thumb_imagesmyfolder_foo.jpg"
without a dash between the last folder name and the file name.