I'm having problem getting jqueryui dialog boxes to open in front of other dialog boxes that are already opened.

I recently upgraded our site to use jquery version v3.4.1and jqueryui version 1.12.1.  Prior to this upgrade it was working fine, but now it is not.

I use popup modals to display other html elements....then I also have links in that popup that open another popup box.  Now if I click on a link inside a modal popup, the other one opens, but its hidden behind the modal popup that I just clicked on.

This is how I initialize the dialog box:

$("#modal_popup_detail").dialog({
           
                bgiframe: true,
                autoOpen: false,
                stack: true, //Puts in front of other dialog's that may be open
                height:h_full_dialog,
                width: w_full_dialog,
                minWidth: w_full_dialog,
                modal: true,
                dialogClass: 'jqueryui_dialog_bg',
                open: function(e) {
                    $(e.target).prev(".ui-dialog-titlebar").addClass("jqueryui_dialog_title_bar");
                    $(e.target).prev(".ui-dialog-titlebar").find("span").addClass("jqueryui_dialog_title"); 
                 
                },
                close: function () {$(this).empty();}
            });

and this is how I call the dialog box:

$("#modal_popup_detail").dialog("open");

Any ideas how to fix this?

Thanks in advance