A multi-city search for a paid ticket US-TPE-ICN-US breaks when looking for the routing from TPE-ICN. It tells me that no flights are scheduled between TPE and ICN on my specified dates - really? Plugging in TPE-ICN on one-way search and there they are

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If it can find me a routing US-TPE, why not TPE-ICN without me having to give it NRT as a connection point?