Restore works, site loads with all post then fails

569 posts are not remapped to new S3 upload URL. S3 migration failed for db ‘default’.

The fact that it says there is a new S3 upload URL indicates that you have configured it differently from the former situation. The fact that it fails indicates that the new configuration is also incorrect.
Solution: make sure the variables set in your app.yml are the same as on the prior install.