Getting `Unsupported request – method type: post` when trying to create an ad account with the Facebook API,use python

“media_agency”: “{my_fb_app_id}”,
“partner”: “NONE”,
“funding_id”: “{my_funding_id}”
}
According to the docs, a POST endpoint is available and valid.I’ve checked if the payment method behind the funding ID is active and valid and it is. It’s assigned to other ad accounts as well and I’m spending money with it.