Do you know possible reasons for this paragraph, which has the exact same configuration of the others, to appear like it?
Looks like there are a couple of extra tab characters in the line.
Check the target paragraph in the document and see if it has the soft-return and extra tabs. These will come over into the TOC.
As Rick mentioned, there is a Shift-Enter (forced line break) after Guide. Remove that forced line break from your heading and update your book.
Thank you everyone! 🙂