Why don't new contacts created on my iPhone sync to my desktop Mac? On my iPhone running iOS 13.3, I can create a new contact in the Contacts app. However, the contacts do not end up in the Contacts app on my desktop Mac (which is running 10.13.6).  I have iCloud on the Mac configured to share contacts, as can be see in the following screenshot:



Similarly, my iPhone is configured to share contacts too, based on the iCloud configuration in Settings ➜ my Apple ID, as can be seen in the following screenshot:



Both the iPhone and my Mac use the same Apple ID.  Neither device is out of disk space, nor is iCloud out of space.  The contacts that are missing from the Mac were created last week, so I think enough time has passed that it's not a time lag issue.

What can cause this problem, and how can I fix it?
Solution 1: Verify new contact default account location

It is likely that while Sync is working, that the contacts aren't syncing because you are not creating those contacts in your iCloud account.

The contacts app has the concept of different places to store Contacts, indeed all iCloud services do this, a more relatable example would be in Apple Mail where you have multiple mailboxes within each email account.

One of the options in both of these Apple applciations is to create things 'On My Mac'.

In this case it's likely you are creating contacts on your Mac or iPhone and not in iCloud.

You can check and fix this by:

macOS


Launch Contacts.app
Click "Contacts" in the Menu Bar, then "Preferences".
Choose the "General" tab.
At the bottom look for "Default Account"


It should be your iCloud account.

iPhone OS


Launch Settings
Tap on "Contact"
At the bottom look for "Default Account"


It should also be your iCloud account.

Solution 2: Signing out of iCloud and back in again

If the above doesn't fix the issue, or is already correctly set to your iCloud account, I would suggest signing out of and back into your iCloud account.


  Warning: As there is unsyncronised data there is the possibility of data loss, you need to manually backup the missing contacts.


macOS


Launch System Preferences.app
Choose "Internet Accounts"
Select your iCloud account
Click the - (minus) symbol to remove the account.
Click the + (plus) symbol to add the iCloud account again.


iPhone OS


Go to Settings
Tap on your profile at the top with your avatar.
Select "Sign Out" at the bottom
If prompted choose "Sign out of iCloud"


Tip: Don't sign out of both at once as it will make login with two-factor authentication difficult to impossible.