Mobile Widget Cause Half Of Screen?

I have a project, one actor + one camera in the scene

Blend The View Target To The Camera In The Level Blueprint

When I pack the project to HTML5, the result is correct.

But, if I Create A Widget And Show It In The Level Blueprint And Pack The Project To HTML5, There Is Something Wrong: The Widget Would Be Shown Correct But What The Camera See Would Be Incorrect, The Camera Would Only Show Quarter Of The Screen With The Position Is Left-Down Screen

What Is The Problem?