This happened to me as well. On Monday evening, April 16, I booked a one way flight CCU-PEK directly on Singapore Air's website. I live in the US east coast so it would have been Tuesday in Singapore, India, and China, for whatever that's worth. That's been about 36 hours ago, and I still have not received an email confirmation of the booking. I have a Krisflyer account, but it shows no bookings. My credit card account shows the transaction, but says "Pending". I don't have a booking reference, so I cannot look it up.

The only confirmation I have is that I had entered two email addresses to share the itinerary. I have received that email on both accounts, but it pretty much only gives the itinerary. There's no booking number or anything else helpful. I entered my United MileagePlus number for accrual, if that makes any difference. However, I was logged into my Krisflyer account when making the reservation.

OP, have you received anything yet? My flight isn't until November, so I'm still almost 7 months out and not concerned about that. I've just never seen this happen before.