On an AAward, one isn't allowed to connect in DOH on itineraries between the US and SE Asia, so that's why it's not pricing together - the only way to book this itinerary is to pay for each segment individually on one itinerary, which is what the 2nd agent is telling you.
Thank you for the clear response. Is the same true for Etihad via AUH? Is there a list to view? Looking for 'cheapest way' to get to HAN or BKK leaving around Jan 5. Sadly, no Alaska Air miles.