picture tag in content control is written without a namespase in output word document

[MajedDH]

I'm using NPOI from NuGet v2.4.1 and MS Word 2019.

here is the files I used to reproduce the bug: INPUT.docx OUTPUT.docx

I've almost done nothing:
1- Open a new blank document.
2- Go to developer tab and insert a new picture content control
3- Save the file somewhere (no special options just a name).

I've used this basic code:

Stream _templateFileStream= new FileStream(@"INPUT.docx", FileMode.Open, FileAccess.Read);
_document = new XWPFDocument(_templateFileStream);
_document.Write(new FileStream("OUTPUT.docx", FileMode.CreateNew));
_document.Close();

when the output didn't open by ms word i used Open XML SDK 2.5 Productivity Tool For Microsoft Office : here are the validation output:

I wonder why it got written without a namespace. When I repeated the same steps but using an image inside the content control , it didn't work. It worked when I inserted a picture (just a very normal picture the normal way without any content controls) and it worked.

Thanks.