When you visit the Table of Contents dialog box, Word includes styles whose Outline Level is set to something other than "Body Text." Typically, this means the built-in headings, at least levels 1–3, but also custom styles with an Outline Level set in the Modify Style dialog box (your document includes some custom headings). This is by design in Word.

The TOC field code controls the actual, current settings for the TOC in your document. If necessary, you can edit the field code to make further customizations, as Charles pointed out.

It is worth noticing that the display of TOC entries in the document is controlled by the TOC series of styles. TOC 1 controls the appearance of level 1 items, TOC 2 controls the appearance of level 2 items etc.

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional