Button events sometimes triggered, sometimes not - wpf

Question

I have a window that looks like this:
<vk:VirtualKeyboard x:Class="Hurst.VirtualKeyboard.QwertyVirtualKeyboard"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
xmlns:vk="clr-namespace:Hurst.VirtualKeyboard"
xmlns:vm="clr-namespace:Hurst.VirtualKeyboard.ViewModels"
DataContext="{DynamicResource keyboardViewModel}"
Height="400" Width="1280" d:DesignHeight="300" d:DesignWidth="710"
x:Name="VK"
>
<vk:VirtualKeyboard.Resources>
<ObjectDataProvider x:Key="keyboardViewModel" ObjectType="{x:Type vm:KeyboardViewModel}" />
</vk:VirtualKeyboard.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="43"></RowDefinition>
<RowDefinition Height="*"></RowDefinition>
</Grid.RowDefinitions>
<Button Grid.Row="0" Foreground="White" Margin="0 3 20 0" Background="#006AB6" BorderThickness="0" Command="{Binding CloseKeyboardCommand}" FontSize="25" Content="Close" VerticalContentAlignment="Center"/>
<Border Grid.Row="1" BorderBrush="#006AB6" BorderThickness="5">
some content here
</Border>
</Grid>
QwertyVirtualKeyboard is a class that extends the VirtualKeyboard class, which extends the Window class.
The problem I am facing is this: When I click on the Close button, sometimes the Close command is triggered and sometimes not. The same things happens with hover - sometimes hover is triggered, and sometimes not. I've noticed that when the mouse is over the bottom side of the button, hover and click work as they should, but when I move the mouse to the upper part of the button they dont. What am I missing here?