I have had this happen to me one too many times. One listing, I spent over 3 hours on and in one click of the button, a one minute hang, boom, the listing was lost and I had to start from the beginning.
I have learned since that once I recognize the hangup within a few seconds of hitting the save button, I immediatly go to copy the description so that at least I have that if the listing is not saved. That simple task has saved me dozens of times!
Best, Paul