According to DerbyDad03 :

But, Doug...of all people ;-) you didn't comment on why only LF2 is on
with the switch off.

See my other posting. When you put a 100W incandescent in series
with a, say, 13W CF, the CF is passing so little current that the
IC bulb may not visibly light up at all, or only have a faint red
glow. If they were both ICs of the same wattage, they'd both light
up (dimly).
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.