Apply pressure. Front and rear systems have equal pressure.
Piston is centered.
Turn on line lock still equal pressure.
Piston is centered
Release pedal and now one side of system has pressure and the other does not.
Piston moves to the no pressure side, light comes on.
Release line lock, both front and rear systems have no pressure,
piston self centers, light goes off.
if you put the line lock down stream of the distro block this should not happen.