WinForms中堆叠透明PNG Panel并切换可见性异常问题求助

我正在制作一个WinForms表单，通过按钮控制多张图片的显示/隐藏，这是测试用例，实际项目逻辑一致。我把5张透明PNG分别设置为Panel的背景图，Panel的BackColor设为Transparent，在设计器里显示完全正常，但运行时图片显示异常。功能很简单，就是通过按钮切换Panel的可见性，奇怪的是Panel不堆叠时一切正常，堆叠后就出问题了。

相关截图：

现有代码 #

窗体加载事件 #

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    PicA.Visible = False
    PicB.Visible = False
    PicC.Visible = False
    PicD.Visible = False
End Sub

全选按钮（BtnAll）点击事件 #

Private Sub BtnAll_Click(sender As Object, e As EventArgs) Handles BtnAll.Click
    If PicA.Visible = False Then
        PicA.Visible = True
    Else
        PicA.Visible = False
    End If

    If PicB.Visible = False Then
        PicB.Visible = True
    Else
        PicB.Visible = False
    End If

    If PicC.Visible = False Then
        PicC.Visible = True
    Else
        PicC.Visible = False
    End If
    If PicD.Visible = False Then
        PicD.Visible = True
    Else
        PicD.Visible = False
    End If
End Sub

按钮A（BtnA）点击事件 #

Private Sub BtnA_Click(sender As Object, e As EventArgs) Handles BtnA.Click
    If PicA.Visible = True Then
        PicA.Visible = False
    Else
        PicA.Visible = True
    End If
End Sub

按钮B（BtnB）点击事件 #

Private Sub BtnB_Click(sender As Object, e As EventArgs) Handles BtnB.Click
    If PicB.Visible = True Then
        PicB.Visible = False
    Else
        PicB.Visible = True
    End If
End Sub

按钮C（BtnC）点击事件 #

Private Sub BtnC_Click(sender As Object, e As EventArgs) Handles BtnC.Click
    If PicC.Visible = True Then
        PicC.Visible = False
    Else
        PicC.Visible = True
    End If
End Sub

按钮D（BtnD）点击事件 #

Private Sub BtnD_Click(sender As Object, e As EventArgs) Handles BtnD.Click
    If PicD.Visible = True Then
        PicD.Visible = False
    Else
        PicD.Visible = True
    End If
End Sub

运行时切换Panel可见性会出现显示异常（有视频演示该现象）。

想请教：代码顺序、Panel堆叠顺序是否会影响结果？希望有人能指出问题所在，或者告知这种实现方式是否可行，感谢帮助。

内容的提问来源于stack exchange，提问作者NickVids