When you change Address Line 1 and Zip code, the backend system will create a new Address Change record, which will be shown in the Contact's Timeline.

If you investigate the Contact form in designer mode, the Address Change sub-grid is using the 'My Open Address Changes' view.

Further looking into this view, you can see the filter condition is like this:

The issue is from the Activity Party: Party equals current user.
If you modify the Address Changes sub-grid to use 'All Address Changes' view, you can get what you expected.

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