Filter for non-synced images

1. Click on the All Synced Photographs special collection.

2. Ctrl+A to select all of the images in that special collection. All synced images in the catalog are now selected.

3. With all those images still selected, now click on the All Photographs collection. The grid now contains a mix of selected images (which are synced) and unselected images (which are not synced)

4. Now go to the Edit menu and select "Invert Selection", so now all the selected images are the unsynced images.

5. Now click on the folder that you are investigating in the Folders Panel.

6. You will see that mix of selected (unsynced) images and unselected (synced) images.

7. Now either add the selected images to the Quick Collection (by pressing B on the keyboard) or add some other indicator so that you can more easily review those unsynced images when they are eventually deselected, e.g. by adding a flag, a rating, a keyword, a colour label., etc.