similar error was seen with LMS integrated with ACS server, when there was protocol difference in LMS Server and ACS Server. All AAA requests make use of TACACS+ protocol , hence login in to CW and authorization will pass. A difference in http/https protocol will in no way affect launching other CW pages , but all functionalities like , import, export devices etc which make use of https protocol.
So when the ACS is in HTTPS mode , its expected to set CW to connect to ACS in https mode. This can be done by selecting the " Connect to ACS in https mode " check box in Server -> Security -> AAA mode setup -> ACS .