Delete Organization API no longer working in Jira Data Centre using OAuth

We have an API request sent from our own Client software that has started to fail after working successfully for a number of years.

The request is to Delete a service desk organization using the endpoint: Sign in to your account[org id].

Authorization is done using OAuth 1.0 and other API requests are still successful using the same authorization method and credentials e.g. GET Sign in to your account

The same request works user a Bearer Token for authorization and I have tested this using Postman and with a PAT for the same user as the OAuth,

The HTTP status code returned for the failed request is 500 and the content is ‘null’. We have not seen anything in the logs in relation to the request.

I’ve tried Atlassian support but have not had any luck. Anyone got any advice or seen similar?