Just went thru this exact problem... Tried everything, reinstalled all of the recent updates (all the way from 6.0), re-installed Rig manager, etc. The fix was re-installing the Kemper driver. The driver was already located in the Kemper Amps folder, so all it took was from Device Manager -clicking on other devices / profiler and then clicking properties and telling it to update driver. Pointed to the Kemper Amps folder with the driver in it and everything is working now.
This was for Windows 10, right?