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I have tried with the same setup of your manifest file and I see no errors. The only way I can get a similar error, after loading the manifest, in the Data Preview, is when I do not have access to the bucket, but as you have access to the file directly this is strange.
Also, when you give access to an S3 bucket from QuickSight, using the QuickSight managed role then you get access to the whole bucket, you cannot specify specific keys or folders, unless you are not using the default role or this one has been modified to not allow some actions on folders.
Can you check if you are using the default QuickSight role and if it has been modified? You can find this in Manage QuickSight, Security and Permissions, Manage, and you should see something like this.
In my case I have modified the policy, therefore I see this warning. If you see something like this, or a different role being used, please check if you have any specific policy that can be denying you access.
I even tried it with a different, existing IAM role, but the error message is the same. My default role has admin permissions, so it is very strange why it is acting this way. Could the issue be in the S3 bucket permissions or something? Running out of ideas.
Just to discard some other things, can you copy these files to another bucket QuickSight has access to and try the same manifest file?
You can see the permissions that QS has on the bucket opening the AWSQuickSightS3Policy which is attached to the quicksight service role called aws-quicksight-service-role-v0
Unfortunately I currently cannot test it out with any other bucket… is there anything else we could test?
URIs work with several files, tested it just now, but still the same issue with URIPrefixes. I have tried the URIPrefix starting from the root of the bucket to the folder that contains the data.
Thank you for letting us know. I would recommend filing a case with AWS Support where we can dive into the details so that we can help you further. Here are the steps to open a support case. If your company has someone who manages your AWS account, you might not have direct access to AWS Support and will need to raise an internal ticket to your IT team or whomever manages your AWS account. They should be able to open an AWS Support case on your behalf.