'Responsive Grid' can be turned off by removing following line from the ReportViewer-Head.ascx:
<script type="text/javascript" src="./Resources/js/shrinkable-grid.js"></script>
How-do-I-turn-off-the-screen-size-Responsive-Grid
This documentation is for the legacy Izenda 6 product. Documentation for the new Izenda 7 product can be found at https://www.izenda.com/docs/