Microsoft.Office.Interop.Word in .NET 6.0 - Change builtin document property

Question

Using the Microsoft.Office.Interop.Word.Document interface in C# you can get/set the document's built-in properties (Author, Title, Subject, Creation date,...) with this code:

dynamic docprops = document.BuiltInDocumentProperties;

dynamic prop = docprops[WdBuiltInPropertyEnum];

prop.Value = VALUE;

Marshal.ReleaseComObject(prop);

Marshal.ReleaseComObject(docprops);

which works fine if the VALUE is string. When the value is the System.DateTime, the prop.Value (for example WdBuiltInProperty.wdPropertyTimeLastPrinted) is set to a new value, but when I read the same property again like

dynamic docprops = document.BuiltInDocumentProperties;

dynamic prop = docprops[WdBuiltInPropertyEnum];

VALUE = prop.Value;

the VALUE returns unchanged date. Any idea why the property of type date is not updated?

Thanks for any help.