recently created Scene doesnt save

okay,

i am on the latest version, i created a scene today and put prefabs in it and saved.
twyce, save scene → save project.

its always empty with like a starting scene.
i just came back from holidays and didnt really changed anything.

also its not asking me to save the scene when toggling between other scenes.

this actually is a huuuge upset for me today, i cant work at all.

thanks in advance,
Ronny

seems like to happen if i only put prefabs/scenes into my scene.