RedShift Serverless / Spectrum / Glue access issue

I'm running the following in RedShift query editor

create external schema customer_schema
from data catalog database 'customer' region 'us-west-2'
iam_role 'arn:aws:iam::<account-id>:role/RedshiftSpectrumRole'
create external database if not exists;

And getting the following error:

ERROR: Unknown std exception when calling external catalog API: ----------------------------------------------- error: Not authorized to get credentials of role arn:aws:iam::<account-id>:role/RedshiftSpectrumRole code: 30000 context: query: 0 location: xen_aws_credentials_mgr.cpp:402 process: padbm aster [pid=15652] ----------------------------------------------- [ErrorId: 1-6222317d-1fb7af7e7869388e5a5866f3]

The role has access to S3 and Glue, and it has been attached to the RedShift Serverless permissions.

I also submitted a ticket to AWS over 4 days ago and have not heard anything back. Can someone help out? Is there something I missed? Or is this an internal AWS error?

Below is the trust relationship for the role:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Principal": {
                "Service": [
                    "redshift.amazonaws.com",
                    "redshift-serverless.amazonaws.com"
                ]
            },
            "Action": "sts:AssumeRole"
        }
    ]
}