Issues with Oracle BPM Rest API integration

Summary

Trying to hit certain GET, PUT and POST API's, but getting a 400 error. Not sure what's wrong.

Content

I am trying to perform certain BPM operations that are given in the below URL:

https://docs.oracle.com/middleware/1221/bpm/bpm-rest-api-ref/rest-endpoints.html

 

However, i'm getting the below error when i try to test these services:

{
    "type": "HTTP://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.1",
    "status": 400,
    "title": "Bad Request",
    "detail": "{\"type\":\"abcs://proxy_auth_problem/unknown_host\",\"title\":\"Unknown Host\",\"detail\":\"Authentication server <server name>: Name or service not known is unknown\",\"status\":400}"
}

Now i've hit the same service on other platforms (YARC and Mendix low code platform) with the same payload, headers and authentication, and I am able to get a successful response. The Authentication Certificate being used in VBCS and other platforms is the same, so i'm not sure what else needs to be done.  (Generated via OpenSSL and uploaded in the certificates section)