However, it is a bit time consuming with a dozen or more. Is it possible to have a link to the original listing so it can be started from Launch Control? Or a button to start them all at once?
I just tested it here and started a listing using GarageSale’s image hosting service. It uploaded without a problem, so I assume this is a temporary problem you had?
My only guess is that your internet connection is too slow and/or your amount of images too high and/or your images too large – and thus causing the timeouts.
It’s worth a try to reduce the max number of listings started at the same time.