I've booked flights from London out to Vietnam on Avios for late-March next year. I'm now planning to book flights to get back in early April, and have noticed that for the end of March and the open dates in April so far there are no business class (and very few economy) seats available except for the double avios ones. When I booked the outbound there was plenty of choice for slightly earlier in March. I've looked at each leg separately and together, and looked at some other options in Europe to fly back to and there seems to be nothing.

I thought Qatar released seats on every flight now - is that wrong? And is there anything known about that is the cause of such poor availability?

Thanks