When RadGridView is grouped from XAML or code-behind, the first item is auto expanded.
In addition the AutoExpandGroups="False" is not respected and it only occurs when the GroupRenderMode is set to "Nested". As a workaround you can set the GroupRenderMode to "Flat".
Posted on:11 Feb 2016 11:49
RadGridView's newer and recommended UI virtualization engine is GroupRenderMode.Flat. The described issue is not reproducible with it. Please open a support ticket if you have any difficulties with migrating to Flat mode.