Imported models are deleted

I imported models from Sketchup 2018 through a .obj file and grapped them to scene(idk it’s name because i’m UE4 noob) window. After that, I saved that project and closed it.

But when I opened it again, models are deleted. Their names were at World Outliner, but I couldn’t find their shapes. What I remember is when I closed this project, UE4 was compiling shader.

Can I see the models again at scene window?

Do you still see them in the outliner?

did you save all or just save?

Oh… I just press Ctrl + S…! Was it wrong?!

Oh Daxter… you’re right. It works! Thx a lot!!