As with MailBeez 2.8 there is a bug causing issues with the clicktracker:

please replace in
mailhive/common/classes/clicktracker.php round line 86:

<pre style="padding-left: 30px;">$rewritten = str_replace('/?', '/&', $rewritten);

with

<pre style="padding-left: 30px;">$rewritten = str_replace('/&', '/?', $rewritten);

if you already have sent out emails, you can “repair” the links with following rewrite rule (.htaccess)

<pre style="padding-left: 30px;">RewriteCond %{THE_REQUEST} /&mid=* [NC]
RewriteRule ^(.*)&mid=*(.*) /$1 [L,NC,R=301]