I took a closer look at the radio 'aerial' on the side windows earlier as I was clearing out the boot. I have the Honda internal blinds to prevent the rear section from heating up.
The wiring on the glass not like the usual demister system of rear windows, but contains a square element at the front and a rectangle towards the rear hatch,
Whilst there are no marks on mine, it does look as though if the compartment has been used to transport something like a plaster panel, or a fixed dimensional object (chair/cabinet), they could get damaged, causing a break in the circuit.
Have a close look around the lines on the two units, (better a feel), there might be some damage.