The "trigger overview" screen item is displayed incorrectly when the "Hosts location" option is set to "Top". Additionally multiple repeating notices are triggered:

Illegal offset type in isset or empty [include/triggers.inc.php:1540]
Illegal offset type in isset or empty [include/triggers.inc.php:1655]
Illegal offset type in isset or empty [include/triggers.inc.php:1540]
Illegal offset type in isset or empty [include/triggers.inc.php:1655]
...

Originally reported by Richlv.