Pls try this in your report view:

<div id="loading" style="display: none;">
    <img src="Loading_icon.gif" />
    <!-- <i class="krpmSpin fas fa-refresh fa-spin fa-3x fa-fw"></i> -->
</div>
<script>
$.ajaxSetup({
   beforeSend: function() {
        $('#loading').show();
   },
   complete: function() {
        $('#loading').hide();
   }
});

You can set CSS rule for the loading div so that its position is absolute and its width, height, top, left match your report area.