PM me your flights and I'll take a look.
I don't think so. I could be wrong, but I have seen a lot of fares, and the price and the rules seem reasonable enough to me. Not every good deal is a mistake.
Miscalculation of the YR/YQ doesn't make it an error fare. (I suppose you could argue that the whole ticket is mispriced, although we have no idea how YQ/YR logic works since it is proprietary---but either way, that doesn't make the fare itself a mistake.)
SEL-SCL great circle is 11,403 miles. There's no direct LA flight from South America to Asia; you're flying via Australia or North America. So I think this is not unreasonable.
A lot of carriers stopped doing HIP checks. You're right, it is not mentioned in the rules I can see. But unusual for ITA to make such a fundamental mistake.
LA is limited to sixteen segments. This is in common with most other carriers. More segments will require paper coupons, and those are not generally accepted any more. You are also limited to three stopovers (if we are looking at the same fare) which for many travellers is a show-stopper.
I would imagine LA has little experience with mileage runners and gamification of their products is probably low on their list of concerns.
Propeller lost their BA ticketing authority for a while over a number of people dropping segments, that is why they are nervous. Are you sure you can't book SEL-SCL-SEL for a similar price?
If we are talking about the same fare, it doesn't appear to be stock-restricted. One of the other carriers on your journey may be willing to issue the ticket.
If we're talking about LA SELSCL IEXEV00Q, it is not scheduled to expire.
V FARE BASIS BK FARE TRAVEL-TICKET AP MINMAX RTG
1 IEXEV00Q I R 3367.00 ---- -/‡ -/12M AT01
PASSENGER TYPE-ADT AUTO PRICE-YES
FROM-SEL TO-SCL CXR-LA TVL-04FEB18 RULE-JEVQ IPRSAA3/29
FARE BASIS-IEXEV00Q NORMAL FARE DIS-E VENDOR-ATP
FARE TYPE-BR RT-BUSINESS CLASS RESTRICTED
KRW 3603677 MPM E30DEC17 D-INFINITY FC-IEXEV00Q FN-
SYSTEM DATES - CREATED 29DEC17/1018
EXPIRES INFINITY