The issue was introduced with an optimization we made for filtering. Generally, its idea is that if the current filter expression is the same as the previous one, all invalidates of the paging/items count, etc. are not executed. In the case of the project we have that illustrates the issue, the custom filtering expression stays the same no matter what the FilterValue is. 

The solution is to create custom QueryableCollectionView and override the OnFilterDescriptorsChanged to:
public class CustomQueryableCollectionView: QueryableCollectionView
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="CustomQueryableCollectionView"/> class.
		/// </summary>
		/// <param name="source">The source collection.</param>
        public CustomQueryableCollectionView(IEnumerable source)
			: base(source, null)
		{
		}

        protected override void OnFilterDescriptorsChanged()
        {
            this.InvalidatePagingDeterminativeItemCount();
            this.InvalidatePagingAndRefresh();
        }
    }

The source of the grid should be set to that custom collection. Thus the check whether the new filter expression is the same as the previous one will not be executed and the UI of the grid will be updated right away.

Hi Walter,

We are currently working on this problem and hopefully we will have a progress next week.