API Error - WPTAPIError: Not Found

Using the WPT service (i.e not a private instance) for an unknown reason the WPT API has started responding with WPTAPIError: Not Found when issuing getTestStatus.
Our code or environments have not changed and all other API calls appear to work successfully. API keys are valid.
Has anyone had similar or can identify why this might occur?

Have been working with the Support team and they have identified changes in the API to support improved security features.
If you are having this problem, update the API to the latest release first and then ensure you have the API key on your command.