Assigning a physical knob to a quick control


I have my list of track quick controls in the inspector, for Halion Sonic SE. I also have my VST quick controls (the 8 virtual knobs of the Halion rack on the right-hand side). I’d like to assign the physical knobs of my Arturia Keylab to Halion quick controls (track & vst), so I go to “Devices > Device Setup > Track/VST Quick controls”. For MIDI IN, I have “All MIDI Inputs”, and for MIDI OUT, I have “Not connected”. I select the quick controls level (e.g. the 1st one), check “Learn”, turn a knob. Cubase picks the knob MIDI CC (e.g. 73), and assigns it to the 1st quick control. I uncheck the “Learn” box, click “OK”. But when I turn this knob again, it moves 3 other quick controls at the same time, not the right one. What am I doing wrong? I have this type of problem for both Track quick controls and VST quick controls.
Thank you.

Are the other QCs that are moving also assigned to CC73?
If so, assign them to something else.