403 :: not a valid key=value pair (missing equal-sign) in Authorization header

[gclift]

When using the OAuth2 to make a request to the /finances/v0/financialEventGroups endpoint, the server is returning the following error along with the auth token (committed for security).

Response:
not a valid key=value pair (missing equal-sign) in Authorization header:

Is there a Use Case Guide that describes how to use the financial API which includes examples with Oauth2?

Thanks!