I've updated to the new 5.7 firmware and updated RM to 2.1.7 but it does not connect to the Kemper.
If I launch Rig Manager first, then switch on the Kemper then I hear the Windows sound as the Kemper is detected but there is no connection to Rig Manager.
If a connect the Kemper first then try to launch Rig Manager then nothing happens and RM doesn't launch.
I also had the same problem with Rig Manager 2.1.6 and Firmware 5.5 - exactly the same symptoms so I just uninstalled v2.1.6 and went back to v2.1.4 which works fine.
Acer PC running Windows 7 (with all updates installed).
Kemper powered toaster.