Whenever I merge a document with an image in the header, the image disappears when the header contains a mergefield which is merged during a mailmerge.
Attached you'll find the document I'm using. Below is the code I'm running (during for example an unittest)
var doc = new Document("test.docx");
Using an older version of Aspose.Words (v188.8.131.52) the mailmerge is executed without any problems; the image is still there.