NoSuchKey
error response when key isn't present.
https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetObject.html#API_GetObject_Errors
We run basic read check before user can enter the bucket, as a way of testing S3 credentials.
You can either contact them, so they get that addressed or if you're willing to provide some test credentials (please send over DM or our support e-mail) we would be happy to implement a temporary workaround for them and include in a next release.
Thanks! (edited)