I am trying to book an award flight to Chile with Alaska miles on either LATAM or American. However when I search for SEA to SCL on Alaska, I get weird results where the connecting flight from SEA-LAX is too late to actually catch the international flight that day. For example, LATAM has two LAX-SCL flights that leave at 3:00pm and 8:10pm on this day. I can see award availability if I search LAX-SCL. But if I search SEA-SCL the SEA-LAX flight on Alaska gets in late and forces me to sleep overnight in LA and catch the LATAM flight the next day. There are plenty of earlier Alaska flights with open award availability.
Is there some weird rule I am missing here or is this a dumb quirk of the search interface?