UMG LoadingScreen does not scale with resolution

I hava a UMG bp called LoadingScreen.
When I create a hud from it and add it to viewport in normal gameplay, all icons in it scale properly with resolution.
When I use it as a loading screen, all icons in it does not scale properly with resolution

How I setup the loading screen is by calling


in c++.

I also tried to use GetViewportSize and GetDefaultResolution in BP,
but all I got was just 0,
even if I call them in tick of LoadingScreen.

Is this a bug that UMG in loading screen is not affected by DPI Scaling, which is configured in Project Settings?

Did you set the Anchor right to fit the whole screen inside the UMG?

Thanks for your quick reply.
This is my slot setting for my icon element: