Camera be invisible in scene view for all my projects

My camera and light can not see in the scene view now. Doesn’t matter the project I already finished or the new one I just create. I can not see them, but they are still in Hierarchy, and the cameras seem not to

show anything except basic skybox background.

@tuinal
You just save my life, due to that, I stop learn unity and try to figure out for 5hours for yesterday, and almost give up blender and unity. Thank you so much.