If a dual monitor is being used it is very possible that the prompt dialogue box is being opened in a non-visible part of the monitor based on remembering prior settings, having been inadvertently been dragged underneath the ribbon bar or to the seconf montior. Run the job definition until you see the "working" message in the status column, and then try and find the hidden dialogue prompt and drag it into the open area of the desktop. If that does not appear to be possible, you can rename the uf80scn.ini file in the user's "/appdata/roaming ... " tree (see Help About) to a backup name, then re-open the image manager and reconfigure it. At that point the job definition should work by having reset the prompt box location to the factory default.