Styles are being created as "Style Name + Not Bold"

I have many styles that are being inserted into the Word document as
“Style Name + Not Bold”, instead of simply “Style Name”. Why would this
be happening?

I’ve found a manual workaround of opening Word and selecting all
instances of “Style Name + Not Bold” and having Word replace it with
the correct style, but this doesn’t help me in I’m trying to
auto-generate a document.

That is a known issue with Aspose.Words.

Please check https://docs.aspose.com/words/net/working-with-styles-and-themes/ for a workaround.