Originally I've created a post here: https://www.infragistics.com/community/forums/f/ultimate-ui-for-wpf/119356/grouping-is-not-update-when-data-changed . So sorry for reposting almost same request but I need an answer.
And I've accepted this since I used a mini project to reproduce the problem. However, after upgrading real solution I figure out that I used wrong type binding and this means I am still facing originally raised problem which seems to be solved for xamDataGrid Field type, but this does not work with UnbouldField which is obsolete, so I've also tried to change AlternateBinding type and this does not work either.
Is this a bug or I am missing something? I've updated the project to reproduce the problem.