Issue with Authenticating OCI REST API calls for DNS

Summary:

We're using PHP to call the Oracle cloud REST APIs for some DNS configuration. However, the code we are trying to use is only getting back 401 Authentication Errors.

Content (required):

What we know so far:

1. Direct CLI works. So, the user config information we are trying to reuse in code is correct.
2. Also tried creating new keypairs and using them in code to sign the request.
3. System clock is only varying by approx 1 min, so that isn't the problem.

Have ran a debug on the CLI command and below is what it gives:

Request: GET https://dns.us-sanjose-1.oci.oraclecloud.com/20180115/zones/exampledomain.com
Not using Expect header...
send: b'GET /20180115/zones/exampledomain.com HTTP/1.1\r\nuser-agent: Oracle-PythonSDK/2.78.0 (python 3.7.9; AMD64-Windows) Oracle-PythonCLI/3.14.0\r\naccept-encoding: gzip, deflate\r\naccept: application/json\r\nconnection: keep-alive\r\ncontent-type: application/json\r\nopc-request-id: 670F2*****7304\r\nopc-client-retries: true\r\nopc-client-info: Oracle-PythonSDK/2.78.0\r\ndate: Thu, 18 Aug 2022 17:39:58 GMT\r\nhost: dns.us-sanjose-1.oci.oraclecloud.com\r\nauthorization: Signature algorithm="rsa-sha256",headers="date (request-target) host",keyId="ocid1.tenancy.oc1..<ID>/ocid1.user.oc1..<ID>/<fingerprint>",signature="===masked==",version="1"\r\n\r\n'