@managerger I am also starting with Akka.net and core ... Here is my understanding (i am sure that others will correct me if i am wrong). When you do an Ask, this is a blocking action and a response is expected .... so if the ask does not get a reply send to it, then it would sit there forever.
Now I understand that when an exception is thrown, the supervisor will try to deal with it .... and if it cant then it will move to its supervisor (and so on), but typically this would mean that that the sender is never going to get the reply that it expects. So you would need to catch the exception somewhere (either in the supervisor, or in the restart of the actor, and use that as the place to send a message to the sending actor).
If any of this is incorrect,i hope someone will correct me :)