I have just added a new heading level (3) to a document. I have successfully created a new paragraph style (using Styles > Modify) and chapter number (using Tools > Chapter Numbering).
The chapter number and paragraph heading appear in the body of the document but NOT in the Table of Contents.
I have tried making changes in Insert > Table of Contents but whatever selections I make in the dialog (Levels and Paragraph Styles) seems to have no effect on the Preview or in my document.
The TOC only shows levels 1 and 2.