Blank spaces where rows should appear are observed in the following situation. You start editing a row or a column, then scroll the row outside of the viewport before the edit was committed. Then sort a column.

This is reproducible only if the GroupRenderMode property of RadGridView is set to Flat. Also, the AutoGenerateColumns property should be set to False and the Columns should be added manually.

Note that the issue is reproducible also in RadTreeListView, which has the GroupRenderMode set to Flat by default.

To work this around, set the GroupRenderMode property of RadGridView to Nested.