When working intensively on a Word document, the content grows with numbered lists and references, and multiple people update the document, the formatting may become corrupted.
The program has the handy "Restore Styles" functionality for this purpose, but it can also happen that a formatting style has entered the document that does not appear in the formatting panel.
This style can be converted into easily by clicking on that particular text and choosing "Select text with similar formatting" from the "Start" menu -> "Edit" -> "Select" -> "Select text with similar formatting.
Throughout the document, all text with that style will then be selected. Then click on the desired style in the formatting panel and the entire document will be updated.