Thanks so much! I'm still can't replicate this on Matrix though when I put in the same dates, etc.
Is it just a matter of manually trying as many combinations/dates as I can?
No I didn't have any problems putting AUH FCO BOS ATL in the routing bar. Don't put EY though as AZ is the marketing carrier for the EY legs. It should show up by itself. Or you could search as a multi-city with a break in BOS.