If photos or videos on your iPhone or iPad aren't available for import into Photos on your Mac
If you're using an iPhone or iPad with iCloud Photos and have Optimize Storage turned on, some photos or videos might not be available for import into Photos on your Mac.
If you're using an iPhone or iPad with iCloud Photos and have Optimize Storage turned on, the original photos and videos are stored in iCloud, not on your device.
When you manually connect your device to your Mac that isn't using iCloud Photos, an alert icon appears in the sidebar that indicates that some content might be unavailable for import.
To import content from your device to your Mac, turn on iCloud Photos on your Mac.
If you don't want to use iCloud Photos on your Mac, you can AirDrop content from your device to your Mac.