Crazy behavior in loop c# wpf

I have a really strange behavior in one of my view models.

First, in this directory I have three csv files. When I start debugging first it goes inside the foreach and then it goes to the first line this.allDatabases.Add(Path.GetFileNameWithoutExtension(item)); and some strange behavior happens in the next step, it goes to the view. I need to get the name of the files and add them in a collection. In another class this method is working good, but now it is just ... I don't know.

For more information, I used Visual Studio 2015 Community and .NET Framework 4.6

I don't have any exceptions. The FileConstants.PATH_TO_DATABASE is a directory, and I have three csv files on it. For a better explanation I will show two pictures.

First

and next step of debug is

And my code:

private ObservableCollection<string> allDatabases;

public IEnumerable<string> AllDatabases
    {
        get
        {
            foreach (var file in Directory.GetFiles(DirectoryPath, "*.csv", SearchOption.AllDirectories))
            {
                this.allDatabases.Add(Path.GetFileNameWithoutExtension(file)); // after first add is go in view and not return back in foreach loop
            }

            return this.allDatabases;
        }
    }

And the view

<Window x:Class="Growthanalyzer.App.Views.Dialogs.NewView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:Growthanalyzer.App.Views.Dialogs"
    xmlns:vms="clr-namespace:Growthanalyzer.App.ViewModels.Dialogs"
    mc:Ignorable="d"
    Title="New" Height="300" Width="300">
<StackPanel Orientation="Vertical">
    <StackPanel.DataContext>
        <vms:NewViewModel />
    </StackPanel.DataContext>

    <ListBox ItemsSource="{Binding AllDatabases}" MinHeight="150" Width="250" />
</StackPanel>

I don't really know what is happening and what is the problem. If any more information is needed just ask me.

How can I fix this bug, and from what is possible to receive this bug?