Why do I see N/A in Indexed URL column?

"Indexed URL" (ranking URL) column shows the actual indexed ranked URL.

It shows the URL that the Search Engine (Google for example) displays/links to for that tracked keyword, even if it's an inner page under the main domain that is tracked. It may differ from the URL you've entered if you have entered a main URL (example.com).

If the term Rank is 101+ (Not Top Hundred), it will show N/A in the "Indexed URL" column. It doesn't mean that it's not being tracked or indexed by Google or any other engine.

Once it will be in the top 100 results you will see the Indexed URL in this column.