I am using RadGrid (2018.3.910.40) with the EnableHeaderContextMenu="true" to allow user to show/hide any columns of the grid. Due to the number of columns being displayed in the grid vertical scrolling is needed. On first load the grid displays 5 columns, if I right-click on any of these columns I can select the option "Select Columns" and a list of all the columns appear and each one is checked. Now if I scroll to display the next 5 columns and right-click to select columns, the columns 2-4 are shown but are not checked anymore. if I scroll again to display the next five, then columns 2-10 are no longer checked and this continue. If I scroll to show the previous columns then those columns are shown as checked. This happens on all browsers.