The border-line AutoFormat (`---` and the others) and the `+---+` table
AutoFormat leave a numbered paragraph alone, but they read only the
paragraph's own numbering. A heading numbered through a heading-linked
Multilevel List carries its number in its style, so both AutoFormats
applied there. At the top of the document, Enter after `---` in such a
heading removed the characters, switched off the heading's number and
left no border, and the next text went into the heading.
Both checks now read the paragraph's resolved numbering, as the list
AutoFormat does.