ListView sections are not updated on item changes

I'm using QML ListView with sections to display content of my own QSortFilterProxyModel. Seems that sections are not updated when some item in a list has changed.
I'm attaching test application (based on Qt's abstractItemModel example) to demonstrate the issue. This application shows list of animals sorted by name.

• Run ./abstractitemmodel
• Click on 'Set best' for some 'CAnimal' item in the middle of the list
  Expected result: 'CAnimal' shall be placed on top of list, Section name on top shall be 'Best'
  Actual result: 'CAnimal' is placed on top of list BUT section names are not updated

I've also found a workaround how to refresh the list ("Refresh list" button in my example) - if you set impossible search criteria, and then unset search criteria - the list will be refreshed with correct section names.