WPF C# MVVM 列表视图未更新

Question

I see similar questions regarding ListView not updating in MVVM, however I have been struggling for quite a while already..
I have 2 classes, 1 of which is part of the other, such as:

    public class Info
    {

        public string Name { get; set; }

        public string Status { get; set; }

        ....

        public ObservableCollection<Content> UserContent { get; set; } = new ObservableCollection<Content>();
    }

    public class Content
    {
        public string Filename { get; set; }

        public string Path { get; set; }

        public string Type { get; set; }

    }

The page is divided into 2 columns, left is itemscontrol and right is a single usercontrol. When an itemscontrol is clicked, it passes the datacontext to the usercontrol

<local:ScreenControl DataContext="{Binding MainPageViewModel.SelectedDevice, 
       Source={x:Static local:ViewModelLocator.Instance}}" />

UserControl contains a TabControl. One of the tab display details from the Info class

.....
<TextBlock Style="{StaticResource localTextBlock}" Text="{Binding Name}" />
<TextBlock Style="{StaticResource localTextBlock}" Text="{Binding Location}" />
.....

And up to here, all is good.

Problem starts on the other tab. I have a button that will OpenFileDialog, browse to video file and add the file to the UserContent. Then the listview should display.

public ICommand AddVidCommand { get; set; }
AddVidCommand = new RelayCommand(AddVid);
public void AddVid()
        {
            if (MainPageViewModel.SelectedDevice is ScreenInfo info)
            {
                OpenFileDialog openFileDialog = new OpenFileDialog();
                openFileDialog.Filter = "Video Files|*.mp4;*.mkv;*.wmv";
                if (openFileDialog.ShowDialog() == true)
                {
                    info.UserContent.Add(new Content
                    {
                        Filename = openFileDialog.SafeFileName,
                        Path = openFileDialog.FileName
                    });
                }
            }
        }

<TabItem Header="Playlist">
    <StackPanel Orientation="Vertical" >
        <Button Content="Add" 
                Command="{Binding ScreenControlViewModel.AddVidCommand, 
                          Source={x:Static local:ViewModelLocator.Instance}}"
                CommandParameter="{Binding}"/>

        <ListView x:Name="fileList"
                   ItemsSource="{Binding UserContent}">

        <ListView.View>
            <GridView>
                <GridViewColumn Width="100" DisplayMemberBinding="{Binding Type}" Header="Type" />
                <GridViewColumn Width="100" DisplayMemberBinding="{Binding Filename}" Header="Name" />
                <GridViewColumn Width="100" DisplayMemberBinding="{Binding Path}" Header="Path" />
             </GridView>
        </ListView.View>
        </ListView>
    </StackPanel>
</TabItem>

Adding MainPageViewModel

    public class MainPageViewModel : BaseViewModel
    {
        public static ObservableCollection<ScreenInfo> Devices { get; set; }

        public static ScreenInfo SelectedDevice { get; set; }

        public MainPageViewModel()
        {
            Devices = new ObservableCollection<ScreenInfo>();

        }
    }

As you probably guessed it, my listview does not update. I can clearly see the info being passed to the class in visual studio via the button command, but the UI doesn't show..

Answer 1

Answer provided by Clemens in a comment on the question:

You are mixing static and non-static members in your classes. Each time an instance of MainPageViewModel is created, the static Devices property value is replaced with a new ObservableCollection, without notifying consumers of this property. Don't use static properties with MVVM.