Follow this steps to reproduce:
- create a class with a Page property and make sure to use the "input" display type
- create a new page and add an object of the class you created
- type "ann" into the page picker: you should get no results
- now go to your user profile and enable the show hidden pages option
- go back you your page (reload) and type again in the page picker
You still don't get any results for "ann" although the Annotations pages are now visible in the page index.