I am posting here for a friend who is not English friendly. He is the primer DHC-6 cockpit builder in France and asked me this question.
On his setup, the cold&dark configuraiton is working fine under FSX but not under P3D v4.5.
It is strange because it works on my side but not on his side. I thought maybe you could have some tip to investigate ?
Here is how we do (does not keep the state on his setup):
I start P3D
Select the DHC6 aircraft and start the the scenario
Within the scenario, I open the addon famous checklist, then select the configuration tab.
In the configuration tab, I select "start cold&dark" and force "switch to cold&dark" if the aircraft is already running.
Last, I save the scenario as is as default
Later P3D start brings the TwinOtter in the cold&dark situation.
I even have the expected behavior on the new P3D v5. I do not understand why not on his setup ?
I can't say why this might be. However, I have not started from cold and dark since I installed 4.5, I was running 4.2 until not so long ago and I did a client-only update to 4.5. Hence I will try it out sometime over the weekend to see if mine still works as expected.