After I enabled Extension:TitleKey search stopped returning results or suggestions for ALL namespaces.
I opened T4045 and the issue was fixed for the main namespace, but not other namespaces.
For example, if you type Project:About or Category:Images, nothing shows up in the suggestions even though that is the exact name of existing pages. If you type Project:Abo or Category:Ima and hit enter, it takes you to a result page without Project:About or Category:Images even though these pages are prefixed with Project:Abo or Category:Ima. Can you please fix search results and suggestions for ALL namespaces? Extension:TitleKey may simply need additional configuration.