It depends how the search keyword was passed on by the search engine. Search engines could use different ways to pass on the keywords info in the URL and its the tracking is not always 100% accurate to capture the keywords
In the cases where default keywords i.e. Query parameter q=Search Keyword is replaced by h=Search Keyword, might not be captured by the Analytics tools. It totally depends how the keyword was passed in the query string by the search engine.
May be someone else can give more accurate answers here.