I've had issues where rules are not saving consistently, or will be there and then disappear when I selected "Forever".
Clients connecting ok and prompting for approval get through but sometimes the prompt window just disappears and that client will never connect at the application level no matter what rule I make to get it through. There wasn't a single deny rule in all of little snitch but the client could not connect.
Very inconsistent performance, I have no idea who made this popular online but there is no way you can run a machine reliably with this software installed. Sorry, this is inconsistent junk.