it seems Adobe had changed the token returned from oauth2.0_token method. It is now something like:

<oauth_endpoint>
request: https://marketing.adobe.com
authorize: https://marketing.adobe.com/authorize
access: https://api.omniture.com/token
<oauth_app> RSiteCatalyst
key: xxxxxxxxxxx
secret: xxxxxxxxx
<credentials> access_token, expires_in, token_type, scope, success

This breaks the following code as sc.cred$access_token, sc.cred$scope, sc.cred$client_id, and sc.cred$expires are all NULL
scc <- list(endpoint.url=endpoint.url,
auth.method=auth.method,
access_token=sc.cred$access_token,
scope=sc.cred$scope,
client_id=sc.cred$client_id,
expires=sc.cred$expires,
debug = debug.mode,
locale = locale
)

I had cloned the RSiteCatalyst source and rebuilt with the following
scc <- list(
endpoint.url = endpoint.url,
auth.method = auth.method,
access_token = sc.cred$credentials$access_token,
scope = sc.cred$credentials$scope,
client_id = sc.cred$app$key,
expires = sc.cred$credentials$expires_in,
debug = debug.mode,
locale = locale
)