question about focus channel fader

[tomcat]

when I select a channel to be controlled by the focus fader, the focus fader doesn't jump to the value if the selected fader. It follows relative motion, though it looks to be a linear relationship, rather than log. as it is in a group. The bigger issue, though, is that when the controlling focus fader gets to the top or bottom of it's travel, the controlled fader jumps from whererver it is to the extreme end. I hope there is something I am not understanding, because this behaivior seems to render the focus fader idea kind of dangerous, if not useless.