Moving this discussion to the Photoshop Lightroom forum.
Somehow the catalog got changed I changed it back and now LR is fine and iPad and iPhone are all synced. Thank you.
Can you advise what actions you did? I appear to have the same problem but I do not understand what you mean about the catalog.
LR was working on my iPad and my iPhone and picking up the Collections I had designated, but I had nothing on my iMac. The catalog is where LR has all your photos and when you downloaded from the Creative Cloud it downloaded everything and assumed you were using the default catalog. At some point I had a problem and to get around it I, unknowingly, created a new catalog with all my pictures. (Doesn’t matter how you created another catalog.) In order to get back to catalog you were using click on File and then click on Open recent catalog or Open catalog. It will list several names with a checkmark by the empty catalog (reason you have no pictures) and click on one the others and you will find your pictures.