A family of Microsoft word processing software products for creating web, email, and print documents.
A first look at your example files doesn't reveal an obvious problem...
When the problem occurs, what does the document look like in Print Preview (File | Print or Ctrl+F2)?
I wish it were something obvious!
Print preview looks the same (no numbers displayed in Print Preview where they appear missing in the doc). The ToC maintains the numbering until the whole table is updated (not just the page numbers). If I put the cursor in a numbered line, then click the Multilevel list dropdown, the area where the numbers should be is gray, as if it still recognizes that something should be there, but nothing is displayed.
As soon as I hit "OK" in the Format-Numbering dialog (from within the Modify multilevel list dialog), the missing numbers magically reappear.