Thanks for your suggestion.I just tried using it with my home laptop. Both work and home latops are on Mac OS but the home laptop's OS is up-to-date.
I'm experiencing the same disappearing T1 in the output device list. The only difference is the T1 worked for 5 mins before disappearing.
I had expect it to either work or not work. I'm quite confounded by this intermittent issue. Right now it's stopped appearing completely.