AWS Ground Truth authorization errors on SOME images

I've followed these tutorials:

Amazon's - https://docs.aws.amazon.com/sagemaker/latest/dg/sms-getting-started.html

Medium.com - https://medium.com/@bruceyanghy/end-to-end-guide-for-setting-up-aws-sagemaker-ground-truth-public-data-labeling-jobs-8732cf49b865

I'm attempting to run a basic object detection (images with bounding boxes) Ground Truth labeling job with Mechanical Turk. I've tried multiple times, opening up any and all security on the S3 bucket containing the images. My past two attempts have been the closest, but still only manage 32/389 images labeled (357 Failed) and 62/389 images labeled (327 Failed). The images are exactly the same in both attempts.

Checking the manifest file for clues, the only error I get is:

<Code>InvalidArgument</Code>
<Message>Requests specifying Server Side Encryption with AWS KMS managed keys require AWS Signature Version 4.</Message>
<ArgumentName>Authorization</ArgumentName>
<ArgumentValue>null</ArgumentValue>

I can't find any references anywhere as to what I need to change to make this work. I've tried with and without server-side encryption on the S3 bucket.

How do I change this signature version?