Moved library to new extern drive - mobile photos now missing

I'm running a Macbook Pro 14 inch.  I keep my library on an external drive.  Using SuperDuper, I movde everything from physical hard drive to an external SSD.  I had some issues and reconnecting the photos from the catalog to the originals in the library, but most of the them are fixed now except for the mobile ones.  I have sync errors showing "original image missing".  Can anyone advise on how to reconnect?