I turned on debug to see if that would help. Here is the output...
Sent INSTEON "Upstairs Office Fan" on
Trigger Test Airfoil
Schedule Test Airfoil (delayed action)
Airfoil Debug runConcurrentThread: update()
Schedule Test Airfoil (delayed action)
Airfoil Debug runConcurrentThread: update()
Airfoil Debug runConcurrentThread: update()
Airfoil Debug update method called
Airfoil Debug update: Airfoil is running
Airfoil Debug update: application sources: [app(u'/Users/Mark/Desktop/Airfoil.app').application_sources.ID(0), app(u'/Users/Mark/Desktop/Airfoil.app').application_sources.ID(1), app(u'/Users/Mark/Desktop/Airfoil.app').application_sources.ID(2), app(u'/Users/Mark/Desktop/Airfoil.app').application_sources.ID(3), app(u'/Users/Mark/Desktop/Airfoil.app').application_sources.ID(4)]
Airfoil Debug update: device sources: [app(u'/Users/Mark/Desktop/Airfoil.app').device_sources.ID(5), app(u'/Users/Mark/Desktop/Airfoil.app').device_sources.ID(6), app(u'/Users/Mark/Desktop/Airfoil.app').device_sources.ID(7), app(u'/Users/Mark/Desktop/Airfoil.app').device_sources.ID(8)]
Airfoil Debug update: system sources: [app(u'/Users/Mark/Desktop/Airfoil.app').system_sources.ID(9)]
Airfoil Debug update: speakers: [app(u'/Users/Mark/Desktop/Airfoil.app').speakers.ID(u'com.rogueamoeba.airfoil.LocalSpeaker'), app(u'/Users/Mark/Desktop/Airfoil.app').speakers.ID(u'F4F951D13A17@Apple TV')]
Airfoil Debug update: Computer (com.rogueamoeba.airfoil.LocalSpeaker) - Connected: 0
Airfoil Debug update: adding to newKnownSpeakers for id: ID-com.rogueamoeba.airfoil.LocalSpeaker value: (u'Computer', u'disconnected')
Airfoil Debug update: Apple TV (F4F951D13A17@Apple TV) - Connected: 1
Airfoil Debug update: adding to newKnownSpeakers for id: ID-F4F951D13A17 value: (u'Apple TV', u'connected')
Airfoil Debug update: setting speakers pref to: Item : (dict)
ID-F4F951D13A17 : (list)
Item : Apple TV (string)
Item : connected (string)
ID-com.rogueamoeba.airfoil.LocalSpeaker : (list)
Item : Computer (string)
Item : disconnected (string)
Airfoil Debug runConcurrentThread: update()
Airfoil Debug runConcurrentThread: update()
Airfoil Debug runConcurrentThread: update()
Airfoil Debug runConcurrentThread: update()
Airfoil Debug runConcurrentThread: update()
Airfoil Debug logging disabled