copy and paste of drawing elements does not work nor duplicating objects

--> Copy,Paste Elemnst like arrow , rectangle does not work
--> menu , duplicate element throws the dump below

Software version: 1.2.9.97-RC1-f1d70720a16bfbcb9caa18c7cfb64c0a125a9c17 (64 bit)
.NET runtime version: 4.0.30319.42000+
Time: 2016-11-03 16:11:32 +01:00
OS: unknown (x64) 6.1 build 7601 revision 10000
GDI object count: 87
User object count: 65

Exception: System.Runtime.Serialization.SerializationException
Message: Der Typ "Greenshot.Drawing.Fields.AbstractFieldHolder+<>c__DisplayClass11_0" in Assembly "Greenshot, Version=1.2.9.97, Culture=neutral, PublicKeyToken=null" ist nicht als serialisierbar gekennzeichnet.

Stack:
bei System.Runtime.Serialization.FormatterServices.InternalGetSerializableMembers(RuntimeType type)
bei System.Runtime.Serialization.FormatterServices.GetSerializableMembers(Type type, StreamingContext context)
bei System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitMemberInfo()
bei System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitSerialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter, SerializationBinder binder)
bei System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Write(WriteObjectInfo objectInfo, NameInfo memberNameInfo, NameInfo typeNameInfo)
bei System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Serialize(Object graph, Header[] inHeaders, __BinaryWriter serWriter, Boolean fCheck)
bei System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph, Header[] headers, Boolean fCheck)
bei System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph)
bei GreenshotPlugin.Core.ObjectExtensions.Clone[T](T source)
bei Greenshot.Drawing.Surface.DuplicateSelectedElements()
bei Greenshot.ImageEditorForm.DuplicateToolStripMenuItemClick(Object sender, EventArgs e)
bei System.Windows.Forms.ToolStripItem.RaiseEvent(Object key, EventArgs e)
bei System.Windows.Forms.ToolStripMenuItem.OnClick(EventArgs e)
bei System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e)
bei System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e)
bei System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea)
bei System.Windows.Forms.ToolStripDropDown.OnMouseUp(MouseEventArgs mea)
bei System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
bei System.Windows.Forms.Control.WndProc(Message& m)
bei System.Windows.Forms.ToolStrip.WndProc(Message& m)
bei System.Windows.Forms.ToolStripDropDown.WndProc(Message& m)
bei System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Configuration dump: