Unbookable fare through OTAs
I am trying to book a multi-city itinerary from DC to India and back in August on UA/LH. I find the rates I want on multiple dates in the first weekend of August through itasoftware, google flights, priceline, expedia, kayak etc, but when it comes to actually booking the ticket, there is always an error. UA web support says that the fare class on LH is unavailable hence unbookable. How are all the OTAs finding the fare then?