Over the last little while, been trying to search multi-city for looking at vacation spots in SE Asia, then to India and back to US, and can't get the site to pull up fares at all, either. Something like SFO-DAD-BLR-SFO. Will not fare it either. If I pull out the middle, intra-asia segment, it will fare it (though not always competitively, for sure, but something like SFO-DAD, BLR-SFO, and then buy the middle segment separately). I always check as with some carriers/routings,as combining together will sometimes offer a better fare than booking separately.

One would think the SQ engine could at least put together the separate fares on one ticket, but apparently not. It just kind of is what it is.