I've made several attempts starting from scratch to get S3 working without functional results. Within AWS's Security Credentials center I've set up a IAM user and assigned AWS's default 'AmazonS3FullAccess' permissions policy. For the user I then generate the Access Keys and copy them to Anahita's plugin, along with the S3 bucket name and folder - both of which are setup in the S3 storage to allow public access (I've put a few image files in these folders and confirmed I can access them publicly). But, when I go to change the Site Admin's avatar nothing is uploaded / no folder for the node is created on S3, although the "broken" image on Anahita's front end is pointing to an S3 location so the plugin should be active.
Comparing my EC2 install to getanahita.com, I see the bucket naming convention in the URL's are different:
I can remove the AWS region and the file is still viewable: