No Notification about new Replies in pC's

I just want to inform you, that the Function, that i get a notification Mail, when there is a new Reply in a private Conversation, seems to be corrupted.

 

I had similar issue. Received 3 private messages about a week ago, only one PM message was notified though email, it seems randomly happened.

 

Now i get no Notification at all anymore, neither for private Conversations, nor for Forum Posts.