CampaignManagementService - GetCampaignsByAccountId : InvalidAccountId

[stvckey]

I'm trying to get an account's campaigns using the following

campaign_service = ServiceClient(
                service='CampaignManagementService',
                version=13,
                authorization_data=self.authorization_data,
                environment=self.ENVIRONMENT
            )



campaigns = campaign_service.GetCampaignsByAccountId(
                AccountId=acc_id,
                CampaignType="Search"
            )

But I keep getting the response

`Web service reported a SOAP processing fault using an unexpected HTTP status code 200. Reporting as an internal server error.
ErrorCode: InvalidAccountId
Code: 119
Message: The account ID is invalid.

I've confirmed through other requests and the front end to confirm that the account ID is correct and have tried multiple different account IDs. I'm not quite sure why I keep getting the error: The account ID is invalid.

Numeric Error Code 119 is not listed in the 'MicrosoftAds' Documentation.

Any help would be much appreciated,
Thanks!