SO I still seem to be able to get the fare to work on those dates at EUR 1764.
My question is that if I look at the BKK-HKG flights on CX on the 9-Feb, they are all zeroed out in "I" class (except one flight). I guess I should just call up BA and try and book, but wondering what other people think of this? Or does booking via BA allow them to get the I inventory through some fancy married segment thing?
Just to report back - it seems that even though Matrix / Google Flights will report that an itinerary is available, there are some quirks to it reporting it correctly. This BKK-HKG sector tripped me up, and I could only book the fare on the sector that shows "I" availability on the CX flight.
Looks like you need to double check availability on this INCEU60 fare for the non-BA sectors before trying to book.