iCloud Photos library shows 6 fewer images than on devices

You probably know this, but it is easy to overlook: If you are using the Shared iCloud Photos Library, you have to make sure, that you have set the google switch to "both Libraries", when comparing the numbers.

When I check my libraries on my Mac and in iCloud, there are also usually different numbers of items.

• On my MacBook Air: Two photos more than own iCloud:

In iCloud:

One reason for this could be, that iCloud Photos is storing duplicate original image files only once, but also different system versions on my devices, that are counting burst photos differently. And I am not sure how the "shared with you" photos are counted, that are not saved to the Photos Library.

And if you have referenced items in your library, that have been imported to Photos without copying them to the library, they cannot be uploaded to iCloud Photos. You can find these referenced items with a smart album with the rule "Photo is referenced".

It is possible to have more photos on device than in iCloud depending on the file format. Although you should only see that on the one device holding the files that cannot sync, not on all devices. File types are listed at Set up and use iCloud Photos - Apple Support

It's likely not a "bug." Continuing with muggy's suggestions, another possibility is that Photos can show pictures on a device even though those pictures are actually in the Photos Library. For instance, pictures transferred to a phone from a computer, especially using iTunes, are considered "temporary" and can't be edited or synchronized with iCloud Photos.

Pictures like this sometimes go to a folder titled "From My Mac."

Corrupt pictures also don't sync with iCloud. On the Mac, you should try making a Smart Folder like this:

with "Photo is unable to upload to iCloud" Honestly, this doesn't seem to work, much. But it might tell you something.

Let us know what you find…

food70 wrote: I just tried it, gave 0 matching objects.

As I said might happen. It's usually videos that cause the problem, but that doesn't seem to be the case here. Finding those 6 pictures could take a lot of work. Because I already have the software, I'd use the trusted 3rd party app PowerPhotos ($40) to search for abnormally small files or other anomalies. But that probably wouldn't find them. You could create another Library and copy this one into it to see if any pictures are rejected.

It might not be worth the trouble…