Hello,

  I'am having a critical bug when I do FlatDataSource.LoadCustomizations which crash all the application. I have added a sample project to reproduce this bug: When launched, try to add a group by field of "book", and then try to filter on books "754K" and "754L", And ou will see on the group by fields "AssetType" and "Book" and with data only on books "754K" and "754L". And then you click Refresh, then the "Item is already added" exception is throwed and application crashes. What happens is that when you click Refresh, it will change the ItemSource by an List of data that doesn't have book 754L, and I think FlatDataSource.LoadCustomizations doesn't like this.

  You just have to launch the sample project and add the field Book and filter, and then click, you will see the bug. Can you please urgently give me a solution to this problem? Because this exception is not catchable and is fatal. Thanks a lot

  Regards