there is a discrepancy between quantity of photos displayed in different places:
as an example a folder "2015" in the screenshot:
1) in the Lightroom folders tree the number of photos in the folder is 3026
2) on the bottom bar of Lightroom 3018 of 3026 are available and I can't find the rest, even if all filters are disabled
3) Finder shows 3020
Synchronize folder doesn't find anything.
Could anybody explain this issue?
Do Photo > Stacking > Expand All Stacks. The status line "3018 of 3026" means that there are a total of 3026 photos in the selected folder (and possibly subfolders, depending on your options), but only 3018 are currently visible. Photos can be hidden by filters (which you have disabled) or by being buried in collapsed stacks.
Thank you, John!
And the rest are virtual copies.
Thank you very much, you save my day.