The problem was actually related to ISO 8601 and Safari #87

Author: lcobucci

public/js/talks/schedule.js

@@ -192,12 +192,12 @@ function createBody(items)
 
 function getItemTime(timeString)
 {
-    var time = (new Date(timeString));
+    var time = (new Date(timeString)).toLocaleTimeString();
 
-    hours = time.getHours();
-    minutes = time.getMinutes();
+    time = time.replace(/\u200E/g, '');
+    time = time.replace(/^([^\d]*\d{1,2}:\d{1,2}):\d{1,2}([^\d]*)$/, '$1$2');
 
-    return hours+":"+minutes;
+    return time;
 }
 
 function getItemsColumns(current, items)

src/PHPSC/Conference/Domain/Entity/ScheduledItem.php

@@ -182,7 +182,7 @@ public function jsonSerialize()
         $data = array(
             'id' => $this->getId(),
             'label' => $this->getLabel(),
-            'startTime' => $this->getStartTime()->format(DateTime::ISO8601),
+            'startTime' => $this->getStartTime()->format(DateTime::W3C),
             'room' => null,
             'talk' => null
         );