Went to try out the standard whitefire headphones (using dual view, TV setting), but can't get them to produce any sound. When turning them on the orange LED flashes once and then goes off. Tried new batteries and checked that the 4 red LEDS in the overhead console are on, but still nothing. Changing channels on the phones also makes not difference

Am I missing something obvious?

TIA

Andy SDV8 AB MY 2019
SDV8 VSE MY 2015 - Gone
5.0 S/C AB MY 2010 - Gone
4.2 S/C VSE MY 2006 - Gone