Perhaps I wrote my previous query too hastily.

The Expert study guide says that one way to create an automark list for an index is to create a two-column table, in which terms to be found in the document are listed in the left column with their associated index listings in the right. It does not indicate how to associate them, so I guessed by row, which I cannot get to work. How else might one associate terms in two columns?

I converted the same list of terms in the left column into a simple, un-tabled list, each term in its own paragraph. Word had no trouble finding and marking the entries this way. I am left wondering why the concordance table method failed, and have not been able to find any clarification of this method in my searches.