I was having the same problem. Switching to Authorize 2.0 fixed it.
Then I saw your post here today regarding upgrading gold cart….so I did that and tried switching back to CIM. No dice.
Switched back to 2.0 and it works fine…but the checkout is uglier for with 2.0 than with CIM and gold cart warns me that you will one day drop 2.0 support.
What other steps should I try to get CIM working?