This seems to be a problem with MIDI Control Center. All the other knobs can be remapped to any other CC, but not 7, it's stuck in the default, 19. I tried manually modifying the JSON file but when importing back it still will parse it as CC 19. Once clear symptom is that modifying the CC value for knob 7 doesn't you an asterisk next to the preset name, it's like no change is made.
Also: there really should be an option for using relative mode for the knobs, like in previous versions of the controller.