Hello

Something very annoying happened to me so if there is somebody with explanation I will be very thankful.
My drawing suddenly disappear. I make some drawing in drawing file let say Ground plan. After I change the drawing file to let say 1st flor and than change again to Ground plan all my work is missing - disappear. So after many trys I want to restart Allplan but stop responding. Is it possible that this is a bug or is something happened with my hardware ?

Thank you in advance

Riko