❔ WPF APP - Media Element Issue

Hey there, so I was trying out a media element in WPF. The XAML window preview displays the video playing. But as soon as I run the application it is a blank white background. I've tried it out by using an image as a background as well, for some reason that doesn't work either. I have restarted the IDE and restarted my PC so I feel like it might be a mistake I'm making. Can somebody help out? PS. I will link screenshots