When creating an map there is an advanced option called ‘Zoom In Search box‘ that is visible when ‘Show Advanced Options‘ is clicked..  The default behavior is to zoom into the items that match the search query.  In some cases this might not do anything if the items in the search query are spread out as much as other items.

To use the search box to only show items matching the query the ‘Zoom In Search box‘ option needs to be unchecked.