So I've seen many people have had this issue and it mostly comes down to a javascript conflict. I've tried all of the methods to fix this that I can find. (disabling all plugins, adding no conflict script to headerinclude etc) non of which seem to work.
My headerinclude template
Code:
<link rel="alternate" type="application/rss+xml" title="{$lang->latest_threads} (RSS 2.0)" href="{$mybb->settings['bburl']}/syndication.php" />
<link rel="alternate" type="application/atom+xml" title="{$lang->latest_threads} (Atom 1.0)" href="{$mybb->settings['bburl']}/syndication.php?type=atom1.0" />
<link rel="icon" type="image/x-icon" href="http://www.forumbomb.com/favicon.ico" />
<meta http-equiv="Content-Type" content="text/html; charset={$charset}" />
<meta http-equiv="Content-Script-Type" content="text/javascript" />
<link href='//fonts.googleapis.com/css?family=Roboto:400,500,500italic,400italic,700,700italic' rel='stylesheet' type='text/css'>
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css">
<script type="text/javascript" src="{$mybb->asset_url}/jscripts/jquery.js?ver=1804"></script>
<script type="text/javascript" src="{$mybb->asset_url}/jscripts/jquery.plugins.min.js?ver=1804"></script>
<script type="text/javascript" src="{$mybb->asset_url}/jscripts/general.js?ver=1804"></script>
<script type="text/javascript">jQuery.noConflict();</script>
{$stylesheets}
<script type="text/javascript">
lang.unknown_error = "{$lang->unknown_error}";
lang.select2_match = "{$lang->select2_match}";
lang.select2_matches = "{$lang->select2_matches}";
lang.select2_nomatches = "{$lang->select2_nomatches}";
lang.select2_inputtooshort_single = "{$lang->select2_inputtooshort_single}";
lang.select2_inputtooshort_plural = "{$lang->select2_inputtooshort_plural}";
lang.select2_inputtoolong_single = "{$lang->select2_inputtoolong_single}";
lang.select2_inputtoolong_plural = "{$lang->select2_inputtoolong_plural}";
lang.select2_selectiontoobig_single = "{$lang->select2_selectiontoobig_single}";
lang.select2_selectiontoobig_plural = "{$lang->select2_selectiontoobig_plural}";
lang.select2_loadmore = "{$lang->select2_loadmore}";
lang.select2_searching = "{$lang->select2_searching}";
var cookieDomain = "{$mybb->settings['cookiedomain']}";
var cookiePath = "{$mybb->settings['cookiepath']}";
var cookiePrefix = "{$mybb->settings['cookieprefix']}";
var deleteevent_confirm = "{$lang->deleteevent_confirm}";
var removeattach_confirm = "{$lang->removeattach_confirm}";
var loading_text = '{$lang->ajax_loading}';
var saving_changes = '{$lang->saving_changes}';
var use_xmlhttprequest = "{$mybb->settings['use_xmlhttprequest']}";
var my_post_key = "{$mybb->post_code}";
var rootpath = "{$mybb->settings['bburl']}";
var imagepath = "{$theme['imgdir']}";
var yes_confirm = "{$lang->yes}";
var no_confirm = "{$lang->no}";
var MyBBEditor = null;
var spinner_image = "{$theme['imgdir']}/spinner.gif";
var spinner = "<img src='" + spinner_image +"' alt='' />";
var modal_zindex = 9999;
</script>
<script type="text/javascript">
var quoteMsg = "View More";
var quotePop = "Too Many Quotes";
jQuery(function() {
jQuery('blockquote:not(blockquote > blockquote)').each(function(a, b) {
jQuery(this).children('blockquote').each(function() {
jQuery(this).html("<div><div class=\"spoilerheader\">" + quoteMsg + " <a href=\"javascript:void(0);\" class=\"spoilerclick\">(" + quotePop + ")</a></div><div class=\"spoilerbody\" style=\"display: none;\">" + jQuery(this).html() + "</div></div>");
});
});
jQuery(".spoilerclick").click(function() {
var spoiler = jQuery(this).parent().parent();
jQuery(spoiler).children(".spoilerbody").show();
jQuery(spoiler).children(".spoilerheader").hide();
})
});
</script>{$myalerts_js}