DialogHost can't take full width and height

My DialogHost can't take up all the space of the screen.
Beyond 1450px in width, the height is reduced in despite of a width already equals to 1920px and height to 1080px in my code.

Expected

Currently

Behavior with a manual modification of the width only (height stays 1080px).

Repo with a simple demo with only one step, "Restore NuGet Packages".

https://github.com/Imperare/PocDialogHost

I use 24" screens.

首先，在还原 NuGet 包后运行链接的 Imperare/PocDialogHost 存储库中的简单演示，然后检查 DialogHost 在宽度超过 1450px 时的大小设置方式。完成标准是 DialogHost 在不降低高度的情况下填满可用的 1920×1080 屏幕，并与预期的屏幕截图一致。