If you notice that SCOM is not properly discovering services on a particular server (e.g. it does not detect the presence of Exchange), you can resolve this by clearing the cache of the agent on the server. This will trigger a new full discovery, and the agent should now be able to detect the new services:

1. Log on the server of which services are not discovered properly.
2. Stop the agent (System Center Management service):

   net stop HealthService

3. Delete the contents of the Health Service State folder, located in the installation folder of the agent.
   (default location: %PROGRAMFILES%\System Center Operations Manager\Agent).
4. Start the agent again (System Center Management service):

   net start HealthService

   The cache will be recreated and a new discovery will take place.
5. The discovery requires a bit of time, but once this is complete, the correct services should appear in the Operations Manager console.