Hi;
I checked your problem. In your old WP install, you picked up images with custom sizes, not the uploaded originals. Custom sized images in WP goes by the name like imagename-WIDTH-HeIGHT format, so since you regenerated them, they are not there anymore.
I have a programatical solution to this problem, which is quite elegant, not resource intensive, etc.
Actually, I have two solutions for this. The one I mentioned, adding a code, other is, also programatically sweep thru your db and rename them appropriately, which involves running the script I wrote on your DB backup.
Anyway, my choice would be the second one, as it involves absolutely no modification to your WP's source code.
I am a master developer with very good WP skills, please check my profile.
Thank you, hoping tro work on this.