Lightroom Classic stopped syncing to the cloud, does nothing now, can't get it to start again

[onlybleeding]

Lightroom Classic was syncing with CC fine with up until 2379 images then just stopped as if it has nothing more to sync, if I add any new photos to my catalogue it doesn't sync any of them.  It says I have 2379 photos synced but 2940 photos total.  I have the whole folder of 2940 photos set up to sync and syncing is turned on in preferences so I can't work out why it has stopped.  I can see in my library all photos have the sync icon up until a certain point and from then on it won't sync anything.   I have no sync errors.  If I go to Preferences > Lightroom Sync it says '0 uploading, 0 downloading, 0 pending'.

[Rob_Cullen]

And are your photos in a Collection that is marked to sync?

"Folders" do not sync!

Do you "add any new photos" to a Collection marked to Sync, either when importing or after importing?

Where do you see "2940 photos total."? Is that in the 'All Photographs' list or elsewhere?

[onlybleeding]

I thought I originally synced them by right clicked the folder and clicking "Synchronise Folder" maybe I didn't do that though...  What does "Synchronise Folder" do then?

I added a new folder called Sync and it Synchronised them.  Is there a way to automatically add all photos you import to the Sync collection?

[99jon]

Are any of the photos from a phone or tablet? If so you need to keep the Lightroom app open on the device for sync to fully complete.

In Lr Classic Synchronize folder has nothing to do with cloud sync. It's a method for importing missing items from a folder on your hard drive.

[onlybleeding]

This is just the photos in Classic that I want uploaded to the cloud.

[99jon]

In Classic you need to put them in a collection and then check the sync button to the left of the collection name. 

[Rob_Cullen]

See "Set up Collections" in this document-

https://helpx.adobe.com/lightroom-classic/help/lightroom-mobile-desktop-features.html

[99jon]

You can set up a folder for auto-import.

You could also make a collection named Sync and use drag & drop. Or use the “B” key after setting as target collection.

See my YouTube video

https://youtu.be/NVNOJVapG6U