I have created an application credential for the compute service and successfully obtained a token.

Access rule:
"service": "compute",
"method": "GET",
"path": "/v2.1/servers"

However, when using the token to retrieve the server list, I receive a Error 403 Forbidden error with the message: 'Policy doesn't allow os_compute_api:servers to be performed. 

But i have a necessary permission within the respective project (member role)

How can I solve this problem?

Thanks in advance