Devel kpr, dpr, dpm, etc. only print after cache flush
hook_field_widget_info_alter() is cached.  Follow these steps to Suppress caching (for development) or to use an external page cache 


  when developing for Drupal you might want to suppress all caching of
  data to make sure new hooks, theme functions, etc are recognized
  immediately.
  
  This will have performance detriments, of course, so must not be used
  in production. To turn on this development mode, add the following to
  your Drupal 7 settings.php file: