  Since the experimental realisation of the integer quantised Hall effect in a
two dimensional electron system subject to strong perpendicular magnetic fields
in 1980, a central question has been the interrelation between the conductance
quantisation and the topological properties of the system. It is conjectured
that if the electron system is described by a Bloch hamiltonian, then the
system is insulating in the bulk of the sample throughout the quantised Hall
plateau due to magnetic field induced energy gap. Meanwhile, the system is
conducting at the edges resembling a 2+1 dimensional topological insulator
without the time-reversal symmetry. However, the validity of this conjecture
remains unclear for finite size, non-periodically bounded real Hall bar
devices. Here we show experimentally that the close relationship proposed
between the quantised Hall effect and the topological bulk insulator is prone
to break for specific magnetic field intervals within the plateau evidenced by
our magneto-transport measurements performed on GaAs/AlGaAs high purity Hall
bars with two inner contacts embedded to bulk. Our data presents a similar
behaviour also for fractional states, in particular for 2/3, 3/5 and 4/3.
