Problem adding a contact in Contacts

Hi dlbcnjdmw,

Thanks for contacting Apple Support Communities!

We understand that you're attempting to add a new contact and the information entered doesn't save.

Are you using iCloud contacts, or do you use a different account for your Contacts?

Are you able to enter new contacts while in safe mode? If you need help to start in safe mode and learn what safe mode does, you can reference this link: How to use safe mode on your Mac - Apple Support

"How to use safe mode

Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:

Apple silicon

1. Shut down your Mac.
2. Turn on your Mac and continue to press and hold the power button until you see the startup options window.
3. Select your startup disk, then press and hold the Shift key while clicking “Continue in Safe Mode.”
4. Log in to your Mac. You might be asked to log in again.

Intel processor

1. Turn on or restart your Mac, then immediately press and hold the Shift key as your Mac starts up.
2. Release the key when you see the login window, then log in to your Mac. 
3. You might be asked to log in again. On either the first or second login window, you should see ”Safe Boot” in the upper-right corner of the window.

If the issue continues in safe mode

If the issue continues while in safe mode, or your Mac restarts several times and then shuts down while starting up in safe mode, you should reinstall macOS and make sure that your Apple software and third-party apps are up to date.

If the issue doesn't continue in safe mode

If the issue doesn't continue while in safe mode, leave safe mode by restarting your Mac normally. Then test for the issue again. The issue might be resolved.

If the issue returns after leaving safe mode, startup items are probably at fault. Apps can install such items in numerous places, and they aren't always easy to find or recognize. For that reason, you should first make sure that you've installed any available updates for your Apple software and third-party apps.

If updating your software doesn't help, try any of these solutions:

• Test your login items.
• To learn whether software in your user account is causing the issue, set up a new user account, then log in to it and try to reproduce the issue in that account.
• Unplug all accessories from your Mac, including printers, drives, USB hubs, and other nonessential devices. You could have an issue with one or more of those devices or their cables.
• Reinstall macOS.

If you still need help, please contact Apple Support."

We look forward to your reply.

Cheers!

Is the Contacts Application associated with a Third Party Service as the Source

In my case, I have Only 1 Source and that is iCloud

If as I suspect, the Contacts application is associated with More than 1 Source - that maybe the cause of this issue.

Should that be correct - suggest Un-Associating Contacts with the Third Party Source.

Then try to add new Contact Information - Does it work as expected ?

refer to image below