I have the exact same problem.
Using the beta 5.6.2 for my Profiler (it also doesn't work with the 5.5.2 software)
Using the 2.1.41 for Rig Manager
Using OS High Sierra 10.13.4
My Rig Manager does not see the Kemper hooked up to my Macbook via USB.
I've tried different cables, rebooting, nothing seems to work.
When restarting Rig Manager it says:
You need to enable Rig Manager’s system extension in Security & Privacy System Preferences.
So, anyone know what to do?
Thanks!