Synchronize folder fails with error 'No photos or videos were found to import'

When synchronizing a Parent folder that contains subfolders in Lightroom CC 2015.2.x/6.2.x, the synchronize operation fails with an error message if the Import dialog is not shown before the synchronize operation.

Error "No photos or videos were found to import."

To correct this issue, update to Lightroom 2015.3/6.3. Launch Lightroom and choose Help > Updates.