Hello Paul,
Well alerts wasn't working for me in previous versions (1.3 & 1.4),
it would hang Radarbox and I would have to restart again.
I'm experiencing the same thing as you, that is.... my first alert message shows
a blank notification box without text, if I shut the notification box without deleting
the message the next alert I then receive all is OK, the notification box appears
on screen with the alert message.
Hope that helps,
Marinus.