In a Word document, for unknown reason, a 4 column table only appears half
in a page. The next row starts in the next page and thus there is half page
blank in my document.

I have tried to select the table in both pages BUT merge table option is not
available. I have attempted to create a new document and copy the table
across but still have the gap. I also find that the checkbox "Allow row to
break across pages" has been selected.

Your advice is sought.