Search Word Document and hide range where Style.localName = "MyStyle"

I have a lot of Word documents where I need to hide text witch is formatted with a custom Word.Style type.

I’m using C# in a Windows Form and I’ve tried to open the Word documents one by one and go through all paragraphs. I then cast the paragraph style to a style object and from this I get the paragraphs Style localname.

Then if this paragraphs local style name matches one that I need to hide, then I try to take the paragraps.Range, select it, and set it to range.Font.Hidden = 1 I then try to save the document, but it document dosen’t change, so text formatted with my custom style does not change.

I've tried this so far:

using Word = Microsoft.Office.Interop.Word;

Word.Application wordApp = new Word.Application();

 private void buttonOpenMany_Click(object sender, EventArgs e)
    {
        List<string> Styles = new List<string>();
        Styles.Add("MyStyle1");
        Styles.Add("MyStyle2");
        Styles.Add("MyStyle3");

        foreach (var item in Directory.GetFiles(textBoxWordFolder.Text,"*.docx"))
        {
            HideByStyleName(item, Styles);
        }

        MessageBox.Show("Done");
    }
        void HideByStyleName(string WordFile, List<string> StylesToHide)
    {
        wordApp.Documents.Open(WordFile);

        Word.Document document = wordApp.ActiveDocument;
        Word.Range rng = document.Content;

        foreach (Word.Paragraph paragraph in document.Paragraphs)
        {
            Object styleobject = paragraph.get_Style();
            string stylename = ((Word.Style)styleobject).NameLocal;

            foreach (var style in StylesToHide)
            {
                if (stylename == style)
                {
                    Word.Range range = paragraph.Range;
                    range.Select();
                    range.Font.Hidden = 1;
                }
            }
        }

        document.SaveAs2(WordFile);
        document.Close(); 
    }

I’ve also tried to use Range.Find.Execute but are having a hard time to figure out how to use this to find text where the Style.NameLocal =”MyCustomStyle1” And also who to replace this found range with Hidden text. Hope anyone have some input or guides.

Thank you and best regards Rasmus