Assets (in assets folder) failing to load locally [Craft 2]
My guess is that your bucket doesn't have the right permissions. Try adding this permission to your bucket (use with caution since this will make the S3 100% public):
{
    &quot;Version&quot;: &quot;2012-10-17&quot;,
    &quot;Statement&quot;: [
        {
            &quot;Sid&quot;: &quot;PublicReadGetObject&quot;,
            &quot;Effect&quot;: &quot;Allow&quot;,
            &quot;Principal&quot;: &quot;*&quot;,
            &quot;Action&quot;: &quot;s3:GetObject&quot;,
            &quot;Resource&quot;: &quot;arn:aws:s3:::bucketname/*&quot;
        }
    ]
}

Replace bucketname with your actual bucket name. You can add this policy via the AWS UI console. In S3 &gt; YourBucket &gt; Permissions &gt; Bucket Policy.
If by doing this you actually manage to get URLs that resolve, then your problem are permissions. I would still delete this bucket policy and set the correct permissions for your use case.