I have confirmed that PowerUserAccess is indeed set.
By the way, is "aws-orbit-workbench-public-us-east-1" an S3 bucket managed by your AWS account?
If this S3 bucket is not under your control, I would not be surprised if the deployment fails.
Another thing to check is that you have not created a deny rule in the bucket policy of the S3 bucket.
Giving S3:ListObject error for bucket aws-orbit-workbench-public-us-east-1 using this config https://aws-orbit-workbench-public-us-east-1.s3.amazonaws.com/deploy/trial_pipeline_cfn.yaml
I have confirmed that PowerUserAccess is indeed set. By the way, is "aws-orbit-workbench-public-us-east-1" an S3 bucket managed by your AWS account? If this S3 bucket is not under your control, I would not be surprised if the deployment fails.
Another thing to check is that you have not created a deny rule in the bucket policy of the S3 bucket.