Any error messages in the console? Also, the later versions of contentstructure searches (the API used here) haven't been able to perform wildcard searches.

E.g when searching for starting terms everything works fine

But when searching for terms inside a title it returns nothing

It looks like you are on the DXP so will use Search and Navigation for the Internal Search, Are you sure the items you are looking for are in the Index ? 

You can add custom Search Providers, some detail here : Add search providers (optimizely.com) 

Do you have any convention that exclude blocks and media from being indexed ?