No search results for specific words

I have recently discovered that specific search words are not returning any results in my project output even though there are many topics in my project with the word. If I search for other words, I get a lot of search results, so search does seem to work, but not for all words. (i.e. when I search for the word health, no results are found even though many topics have the word health. If I search for the word case, I get many search results). I checked to ensure the topics don't have "exclude from search" selected. 

Any help is appreciated.