I noticed the following, is it a bug ...?
on a workstation object :
when asking to "put an image on a wks on next boot",
if the image specified contains add-on images and
if one of this .ZMG file is missing
the workstation imaging will loop forever or
until the missing .ZMG is back, I think it's because
the flag "put an image" is never cleared.

The imaging should give a error or warning and wait for user input,
shouldn't it ?

PS : I had this issue when re-creating image application, the ZMG file