For create case API calls failing with 404, kindly check the group Id that you are using to send the request. The users get a 404 error, if the group Id used to request creating cases is not correct or does not belong to the account.
Also, make sure that the group Id that you are using to create case has screener permissions as a role assigned to it. This can be checked using the admin panel of the WC1 UI.
For Monitor OGS, can you please provide us the response header and payload and the request headers and the payload so that I can look into this.
Please specify the environment you are connecting to: Pilot or is it production?
If this is a production issue, we request you to raise a ticket with the support by clicking the link below: