SCIM: The request contains invalid parameters or values

Hello,

I am trying to connect to a Target System using oAuth authentication method via SCIM. We are using the version 9.0 LTS.

We populate all the correct values and when we try to test the connection we get the below error message:

Error returned: {"error": invalid_request", "error_description": The request contains invalid parameters or values."}

Error returned: The remote server returned an error: (400) Bad Request.

I tried to do a Postman request using the correct access token, client ID and client secret and we manage to return the users and groups. In Postman it seems to be working, while Sync Editor doesn't recognise the connection info.

I tried to reach the server without the authorization token and then I am getting a different type of error message with HML headers: Unauthorized. Proper authorization is required for this area. Either your browser does not perform authorization, or your authorization has failed.

In the meantime, out of curiosity, I tried to mimic the behavior of Sync Editor to Postman by doing the request in a different order and I got the same error messages. 

My question to you is, have you seen something similar before? Is there any specific order the sync editor follows to achieve an oAuth request? 

Thank you in advance!