A few times I have had to edit an invoice after it's been paid - text or description edits only (no price adjustments). Each time, the left-most "Paid in full" marker adjusts to the time the invoice was edited/marked as sent after editing.

When clicking the Invoice Payment History, it shows the correct payment date.

Clicking the left-most "Paid in Full" button that brings up the Activity list shows the correct payment date.

But the first-glance Paid in Full date is no longer showing correctly.