diff --git a/laborious/activities/gates.py b/laborious/activities/gates.py
index caa9eaa..919a2b2 100644
--- a/laborious/activities/gates.py
+++ b/laborious/activities/gates.py
@@ -318,11 +318,13 @@ class Gates(BaseActivity):
 
         data = DataFrame(input_data['data'])
 
+        self.debug(f"Input data: {data.to_string()}", metadata)
+
         if data.empty:
             return now().strftime(DATETIME_FORMAT_WITH_TZ)
 
         max_timestamp = max(
-            data['timestamp'].values.tolist()).strftime(DATETIME_FORMAT_WITH_TZ)
+            data['timestamp'].values.tolist())
 
         self.info(
             f"Last timestamp: {max_timestamp}", metadata)