How can I tell if ASL is blocking something?

If ASL blocks anything, it will log that action. Just log into the ASL GUI, trigger the event, or type in the IP address into the Event: box in the Security Events window. If ASL has anything to do with this event it will report it in the Security Events window. If you do not see any reports related to this event try setting the filter by level to 1, then trigger the event again or if you are looking for an IP, domain name or specific event type in the search words you wish to use in the Event: window.

If you do not see ASL reporting anything related to your event, then ASL is not causing this event to occur.