Hi
My Kemper Rack set 100 % brightness of all Buttons and LEDs after switching on.
I saw the 3 years old discussion about very same problem with Kemper Stage. That was stated as firmware bug.
My Rack has latest FW - 8.7.10.38833
I don't know if firmware related issue because I bought this Rack used. So I can't tell if there was this bug in previous FW releases.
EDIT
I switch off and on with different setting and found that problem exists if I set zero values.
For example I set buttons brightness on 6.0 and collars on 0.0.
In this case after powering up the unit all buttons keep brightness as it set, but collar brightness is 100 % until I touch knob a bit.