Since switching to the iCloud Photo Library, the Photos app on my laptop has kept telling me that
- 1 Item on This Mac Only
- Unable to Upload 9 Items
To identify the oddball photos, I created the following smart folders respectively:
- [Photo] [is] [referenced]
- [Photo] [is] [unable to upload to iCloud Photo Library]
Referenced photos can be consolidated into the library and would then be uploaded to iCloud — mine was a duplicate, so I just deleted it. The photos that could not be uploaded were photos that had been deleted, but somehow a reference had been kept or imported.