SharePoint Online 2013 Workflow calling external web service with bearer token

I am trying to call a Dynamics CRM Online web service from a SharePoint 2013 workflow in SharePoint online with a HttpSend activity. I am unable to get the call to authorize. The workflow does not automatically send any token for authorization. I’ve tried getting a token and setting the authorization header manually, but the authorization header seems to be stripped off the request if the header value contains “Bearer”, verified by capturing the Http traffic with Fiddler. Both SharePoint and CRM in this case are apart of the same O365 setup and are secured by the same Azure AD directory. I’m hoping someone can validate if this is possible, and if so, point me in the right direction to get it set up.