LR CC lost images in collections - use backup catalog

[hugh.letheren]

After losing images in my collections I have tried to use a backup catalog.  The backup catalog has all the images in the right place but it will not sync.  Sync is paused because it recognises that it is a backup version. Deleting all data in the preferences tab, lightroom mobile makes no difference.  How do I force my backup catalog to sync with cloud and my tablet please.  Or how do I recover the images which no longer appear in what were my synced collections!

[JP Hess]

Did you replace your "main" catalog with the backup catalog?

[hugh.letheren]

I did.  I have access to both the main catalog and the backup.  I want to use the backup to restore my synced collections to my desktop (which are present in the backup) to my tablet which have inadvertently been removed from both tablet and the main catalog.  LR keeps telling me to delete my lightroom mobile catalog in my browser.  I do not know what this means!!!!

[JP Hess · Accepted solution]

It is only possible to have one catalog synchronized to Lightroom mobile. If you want to synchronize the backup catalog then it will be necessary to go into the preferences and remove all synchronized data in the main catalog and then stop synchronization in that catalog. Then you can start synchronization in the backup catalog. But you can't have synchronization in both catalogs.

[hugh.letheren]

With your help, I have solved the problem.  As you suggested, I needed to unsync main catalog first and that did the trick.  I do not understand why I had a problem in the first place.  i wanted to reduce the numbers of images on my tablet so tried to unsync somew of my collections but it did not reduce the number of synced photos.  So I did a remove sync on all the images in synced photos on my desktop which worked but it also removed all the images from my collections, which was a disaster.  LR should have removed them from my tablet and from the synced images tab but should have left them in their collections!  very odd. . . . Anyway, thank you for your help - all other attempts to find a solution failed.