Sandbox funding for broker not available

Anyone else not able to deposit using the broker through the API testing? Im getting an “invalid relationship_id”
when i change bank_id to relationship_id, I then get a relationship/bank not found.
Any help would be great, thanks!

You have to create an ach relationship or bank account first before funding your account. Only ach works in sandbox.

You can follow this guide for more info.
How to Fund an Account via Broker API (