HTTP Error ExAws Timestream - [warning] ExAws: HTTP ERROR:

I seem to be missing something crucial/basic when requesting info regarding my Amazon Timestream tables.
When I run ExAws.Config.new(:timestream) on production, I get (with credentials omitted):

%{
  debug_requests: true,
  host: nil,
  http_client: ExAws.Request.Hackney,
  json_codec: Jason,
  normalize_path: true,
  port: 443,
  region: "aws-us-gov-west-1",
  require_imds_v2: false,
  retries: [max_attempts: 10, base_backoff_in_ms: 10, max_backoff_in_ms: 10000],
  scheme: "https://",
}

I removed the credentials for this post but access_key_id, secret_access_key, and security_token do appear so I am led to think configuration might not be the issue.

Then when I test a simple request
ExAws.Timestream.list_databases() |> ExAws.request()
I see the following:

14:01:19.105 [warning] ExAws: HTTP ERROR: :nxdomain for URL: "https:/" ATTEMPT: 1
14:01:19.159 [warning] ExAws: HTTP ERROR: :nxdomain for URL: "https:/" ATTEMPT: 2
14:01:19.204 [warning] ExAws: HTTP ERROR: :nxdomain for URL: "https:/" ATTEMPT: 3
14:01:19.291 [warning] ExAws: HTTP ERROR: :nxdomain for URL: "https:/" ATTEMPT: 4
14:01:19.402 [warning] ExAws: HTTP ERROR: :nxdomain for URL: "https:/" ATTEMPT: 5
14:01:19.482 [warning] ExAws: HTTP ERROR: :nxdomain for URL: "https:/" ATTEMPT: 6
14:01:20.117 [warning] ExAws: HTTP ERROR: :nxdomain for URL: "https:/" ATTEMPT: 7
14:01:20.934 [warning] ExAws: HTTP ERROR: :nxdomain for URL: "https:/" ATTEMPT: 8
14:01:21.591 [warning] ExAws: HTTP ERROR: :nxdomain for URL: "https:/" ATTEMPT: 9
** (MatchError) no match of right hand side value: {:error, :nxdomain}
    (ex_aws_timestream 0.5.1) lib/ex_aws/operation/endpoint_discovery.ex:32: ExAws.Operation.ExAws.Operation.EndpointDiscovery.handle_endpoint_operation/2
    (ex_aws_timestream 0.5.1) lib/ex_aws/operation/endpoint_discovery.ex:19: ExAws.Operation.ExAws.Operation.EndpointDiscovery.perform/2
14:01:26.490 [warning] ExAws: HTTP ERROR: :nxdomain for URL: "https:/" ATTEMPT: 10

In mix.exs I have

{:ex_aws, "~> 2.3.2"},
{:ex_aws_timestream, "~> 0.5.1"},

Any ideas?
Thanks