HTTP 401 UnauthorizedException

For several days my CC v3 API calls were working both in Postman and in my R Script.  Yesterday the calls started failing.  I am successfully retrieving the OAUTH token, but after passing it to the final GET call, I am getting the response below.  Any assistance would be appreciated.  

https://api.cc.email/v3/contacts?status=unsubscribed&include=custom_fields&limit=500&include_count=false&client_id={client_id}