In Confluence before 6.14.0 you were able to type partial words like "proj" into the search box in the header and match pages with titles like "Project X documentation"
As of Confluence 6.14.0, when you do the same thing, it will only match that document if the full word is typed. i.e. you have to type "project"
This behaves the same way that advanced search used to behave before Confluence 6.14.0 which means it does not do partial word matches but does do stemming to try and match different forms of the same word (so "projects" would also match "Project X documentation"). While this change in behaviour is not a bug, it can break workflows where documents of certain projects may have prefixes that used to match in the suggestions but no longer do.
In resolving this, Atlassian should be mindful of potentially impacting customers for whom matching documents based on a prefix would cause too many unwanted results.
Users can add an an asterisk ( * ) after the search term to expand the search. In the example above, searching for "proj*" will match "Project". However, this will match it in all fields of the document and not just the title as it did in older versions.