Newer photos do not, so are clearly not in the photos moments or events. Any help would be most appreciated.
How did you import the new photos since July 1? Did you import directly from the card to your Phots Libray? Or have you been transfering the photos wirelessly using iCloud Photo Library, My Photo Stream, or Shared Albums from a different mac or a mobile device?
As I said above - any photo imported to your library has to be in a Moment. It may be hidden however, and then it will only show in "All Photos", but not in Moments and Collections.
If the Hidden album is empty, and you are still having a discrepency in numbers between All Photos and and "Photos", the missing photos have not yet been imported to your Photos library, for example, because they are in your Shared albums.
Or you Photos library is corrupted. In that case make a backup of the Photos library, if you do not have a current backup copy,
and then try to repair the library with the First Aid Tools.
- To launch the "First Aid Tools" in Photos hold down the options-command keys ⌥⌘ while double clicking the Photos library.
- Select "Repair" in the panel that will pop up. Don't try a repair without having a backup copy of the library.