Microsoft graph directory role delta error

Question

Hi

I'm using first party app to call msGraph beta APIs from our app.

We have successful call to Users delta.

When trying to call directory role delta, this is the url created

[https://graph.microsoft-ppe.com:443/beta/directoryRoles/microsoft.graph.delta()

get the following error: "The requested media type is not supported. The allowed values are json with minimalmetadata"
But the request has these headers:
"Prefer", "return=minimal"
"Content-type", "application/json"

also when trying to call directory roles delta API in graph explorer PPE I get the following error: "Unsupported query parameter(s). deltaLink is required."

any suggestion for possible solution?