photos not imported to mac from iphone

How are you attempting to do the import? Can you tell us a bit more?

• Are you using iCloud Photos to synchronize your devices? If so
• …Do you have “Optimize Storage” checked in Photos’ Settings
• …Do you see all your iPhone pictures at iCloud.com?
• …Do you see all your Mac pictures at iCloud.com?
• …Have you checked to see if the Apple Account is really really the same on the Mac and on the iPhone and at iCloud.com?
• …Do you have more than 10% free storage on your iCloud account?

• Are you using a cable to connect your phone and Mac? Can you tell us specifically what you are doing?
• If you're using a cable, does the Mac ask you to unlock the phone? Try this: make sure that the phone is locked before you pug it in, and wait for the Mac to ask you to unlock it.
• Where does your Mac's Photos Library reside-- in the Pictures folder of your internal drive, or on an external drive? or on a network? on iCloud drive?
• What is your storage on this iPhone? At Settings>General>iPhone Storage, my phone says 50.5 GB of 128 GB used. What does yours say? Do you have more than 10% free storage on your iPhone?
• What is your storage on this Mac? At System Settings>General>iStorage, what does yours say? Do you have more than 10% free storage on your Mac?

What have you tried?

• Have you tried a forced restart? 

Force restart iPhone - Apple Support

This is different from a simple Power Off. I had to continue holding the button down past the "slide to power off" message, and then I released the button only after  the Apple Logo appeared indicating a re-start. 

• Have you tried using the Image Capture app from your Applications folder?
• Have you tried to restart the Mac?
• Have you tired to re-start the Mac in Safe Mode. This bypasses certain potentially disruptive processes, and it often helps. Safe Mode is different for different computers, so see this: 

      Start up your Mac in safe mode - Apple Support 

If safe mode works, see if it continues after going back to normal mode.

About the questions I asked:

• Did you ensure that the iPhone was locked before you plugged it in?
• Do you have more than 10% free storage on your iPhone?
• Do you have more than 10% free storage on your Mac?

Try this:

• Use another library if you have one, or make a small test Library with a few pictures in it and see if the same thing happens. You can create a new Library by closing Photos and then option-clicking on the Photos icon.
• Make a new user and see if the same problem recurs with it.  This is a bit harder, because a new user can't access a different user's stuff. You would need to temporarily move your Library out of your own user's Pictuers folder up to the general "Users" folder.