I have an iPhone 7 running iOS 12.1.4, and a MacBook Pro running OS 10.13.6. I am running iCloud using the same ID, syncing contacts from both devices. This should sync seamlessly, but it doesn't. I have duplicates on the Mac, and the iPhone; contacts that appear on the Mac, and not the iPhone; and contacts that appear on the iPhone, and not the Mac. I want to merge the two databases into iCloud, and eliminate duplicates. I have tried logging out of iCloud on both devices, waiting 30 minutes, and re-connecting. I still have the same issue. Any suggestions as to how I can get my contacts in sync in all three locations would be greatly appreciated.
To remove duplicate contacts:
Make a copy of your contacts.
From the Card menu, select Card > Look for Duplicates.
When asked, click Merge.
Repeat steps 2 and 3 until no duplicates are found.
Make another copy of your iCloud Contacts.
Then sync those contacts to iCloud.
Afterwards, turn off contacts on the iPhone in iCloud settings, remove all remaining contacts and turn it on again.