So I tried to put together a trip on 2 separate tickets: LHR-MCT-LHR (BA, Y) with MCT-BKK-MCT (QR, A/J) nested.

I managed to snag MCT-BKK-MCT for 23/4 - 29/4 in QR J for a bargain £600 just before midnight on 28/2.

When I had looked just before booking, LHR-MCT on 22/4 and MCT-LHR on 1/4 were available. By the time MCT-BKK-LHR had ticketed (less than 10 mins), it seems that availability on the return MCT-LHR on 1/4 had disappeared.

Can anyone help me with checking what has happened to this flight? Has it been cancelled or is there just no inventory left? Do I have any options or am I left holding a ticket from MCT with no positioning flight?