I have few titles in index file and the corresponding metadata in that one of the title is Dictionnaire de termes du droit des affaires (Série du dictionnaire de droit de Black)
Now when searched with dictionnaire de droit de it is fetching the title but if we search with dictionnaire de droit d it is not fetching the results.
Happening with the out of the box search and results components, and also with the custom developed component.
Have the logs revealed anything? You can compare between when it works and when it doesn't.