Hello,
I have a problem with the same message. I did a migration, but instead of putting the images I need to synchronize in the correct place for the first time I didn't do it.
So All my categories and products got migrated, but with no images.
So I got all of the images I needed from a backup I had and copied them in the correct locations. So I then tried to synchronize everything again, so that my images will show in the store. But no images are getting transfered no matter what I do.
Same notification, and I only have an option to start a migration and not "Resume".
Help Please.