Suddenly unable to close any message (Vaadin 7.5.5)

I am using different messages of all types (i.e. Notification.Type.HUMANIZED_MESSAGE and Notification.Type.ERROR_MESSAGE). And although I haven't changed the standard behaviour, I find myself suddenly unable to close any of them. It doesn't matter where I click, the messages remain open, and I need to restart the application to get rid of them.

Has there been a change in how messages are dealt with in the newer Vaadin versions?

The way I create them is as follows:

@Override
public void sNotify(String message) {
    new Notification(message, Notification.Type.HUMANIZED_MESSAGE).show(Page.getCurrent());
}

I tried to reproduce this in a simple application with nothing else than a button which opens a notification - worked just as expected. Do you have some custom theme or add-ons in your project that might cause this behavior?

I've got it! I left a lock open in one of the threads I started:

UI.getCurrent().getSession().getLockInstance().lock();

Thanks for your help Kim.

Sascha Zevenhuizen: I've got it! I left a lock open in one of the threads I started:

UI.getCurrent().getSession().getLockInstance().lock();

Thanks for your help Kim.

Hopefully, you are aware of the access() method.
 

I am:

// Update the UI thread-safely

            UI.getCurrent().access(new Runnable() {

                @Override

                public void run() {

                    view.updateStatus(newStatus);

                }

            });

but this lock was different. I had to set it to allow changes to a data container that only exists in the thread. I don't understand why, I have to dive deeper into this matter since I'm still a bit of a newbie when it comes to multithreading.