Originally Posted by
findark
Seems to be a precompute failure. It is pricing the trip to SIN with a stopover in MLE until you click through and choose a return that isn't MLE-SIN-SFO. This will show the correct price ($2,xxx in M).
This is mildly common for very complicated routings where the computer is probably hitting a computation timeout and giving up prematurely. Note that you may also see price differences on similar routings as UA and LH inventory for the same FRA-SFO flights are different, and Google can force ua.com to sell LH native inventory (sometimes).
Likely answer, booked as a multi-city UA gets the right price for the chosen routine and a cheaper price returning on UA. Not usre I would pick more expense LH economy over cheaper UA
Have learned it is worth checking multi-city with partner flights. And easier to find prefer connections.
UA also get the right price if you do standard RT but set FRA as preferred connection (in advance search)
So clearly the simple search is not finding the flight (premature timeout as suggested?)