The light on my switch is on all the time, as far as I can tell. I wonder if the coding of the rear lights to be always on cou ld have changed this behaviour. I'm pretty sure it's always been like that, though.
Exactly this - if you code the rear lights to always be on, then the green 'headlights on' indicator on the light swich is always on when in Auto, rather than responding to theheadlight status.
I preferred knowing when the headlights were on, so cancelled the coding for 'rear lights on with DRLs'.