To reproduce:
- Enable the alternating row color and change the current cell as fast as you can.

Workaround:
void radGridView1_RowFormatting(object sender, RowFormattingEventArgs e)
{
    if (e.RowElement.RowInfo.Index %2 ==0)
    {
        e.RowElement.DrawFill = true;
        e.RowElement.GradientStyle = GradientStyles.Solid;
        e.RowElement.BackColor = Color.Aqua;
    }
    else
    {
        e.RowElement.ResetValue(LightVisualElement.BackColorProperty, ValueResetFlags.Local);
        e.RowElement.ResetValue(LightVisualElement.GradientStyleProperty, ValueResetFlags.Local);
        e.RowElement.ResetValue(LightVisualElement.DrawFillProperty, ValueResetFlags.Local);
    }
}