I've had this happen, too, in a document I created myself, with tables I
created myself--could not find anything wrong with them but could not get
them to join. In your case, I missed the fact that you had a page break. Did
you check the first row of the second table to see if it was formatted "Page
break before"? This won't actually split the table (the rows on the second
page will be part of the same table), but it will cause that part of the
table to be on a new page.