Migrating Notebook instances from AL1 to AL2 (notebook-al2-v2)- create a sync to new instance

Hi all, I can't successfully create a sync from a snapshot to a new instance, I have managed to create the backup but not the sync. I followed the steps in this : https://aws.amazon.com/blogs/machine-learning/migrate-your-work-to-amazon-sagemaker-notebook-instance-with-amazon-linux-2/ .

Any idea how to fix this? Thanks in advance