Could not perform remote backup or restore. MissingAuthenticationToken: Request is missing Authentication Token

Hi guys, we are trying to perform backups to S3 following your documentation and having some troubles to achieve it.

The error we are getting is:

Could not perform remote backup or restore. MissingAuthenticationToken: Request is missing Authentication Token

We have checked that the EC2 Instance Role has the appropriate permissions to write in the destination bucket.
Can you guide us to tackle this issue?

Thanks in advance
Best regards
Santiago Respane