Send within doctrine.onFlush listener

[Psiiirus]

Hiya,
I'm wondering why my push-notifications don't get send if i add the call tp my onFlush listener.
I debugged everything and my created message objects do looks perfectly fine but after passing them into the send()-method of the notification-service nothing happens.

Is there any restriction within the kernel lifecycle?
Another thing i just noticed is that the RMSPushNotificationsBundle kernel.terminate listner never gets triggered, is this just a fallback or a bug?

Cheers,
Toni

Symfony: 3.3
RMSPushNotificationsBundle: 0.2.3