I have recently noticed this problem and have successfully isolated it to being an issue with Kemper's Volume Pedal technology.
As long as I don't touch my Volume Pedal, everything works as expected and volumes between patches and system are maintained correctly.
However, as soon as I touch the Volume Pedal, everything gets messed up.
Also, as soon as I unplug the Volume Pedal, the issue is immediately resolved.
As a temporary workaround, I've configured my patches to just have a volume increase when I click a the currently activated switch a second time.
This is definitely an unacceptable issue for any professional environment and I really need to get this resolved.
Any feedback is greatly appreciated.
I'm also going to follow up with Tech Support and will update this post if I learn anything useful.
Current OS - 8.6.6.32765
OS Build Date - Oct 26 2021 16:53:29
DSP Date - Sep 17 2021 15:24
I'm using the Kemper Profiler head with built in 600w amp.
I always run directly to Front-Of-House in stereo for all gigs and never use the power amp.