UIs only expire in debug mode

Hi,

I need to detect when a user has closed a UI in some cases in my application. To do so I have added a detachListener and set a heartbeat of 30 seconds. A UI expires after 3 heartbeats are missed, so that means that after a minute and a half this listener should be triggered. And that's exactly what happens in my development environment where I start the application in debug mode in my intelliJ (GlassFish server).
However, if I start the application in Run mode, the UI doesn't expire. If I deploy the application in the GlassFish panel, it doesn't work either.

So my question is, how can I make this work even if I'm not running the application in debug mode from my IntelliJ? What am I doing wrong?
 

I found out that more people have this problem:

https://vaadin.com/forum/#!/thread/1939777/1939776

Nobody has a clue?