(new user) differents levels vanished on play

(New user question) I’m triing to set a global scene with multi levels. One for the 3Dmeshes and others for lightings. I just test with 3 of them (lights + props + persistant) but when I hit play the lighting level and the props levels disapears. why? (all levels are on 'always loaded)

Okay, I’ve found an exit. The problem is : you have to check all levels with right clic and make “always loaded”. For each of them. BUT If you check ALL levels and make them “always loaded” it doesn’t work… Why? So exasperating…