I have an Economy (H) ticket DFW-DOH-HBE (two-way / return) in July and I have enough points to upgrade both legs using Avios, but when I try to upgrade online it says "There are no seats available for award upgrade".

But if I search as if I'm booking an award flight, I see the exact flights available.

I was thinking if an award flight is available surely a seat upgrade is also available? It doesn't work that way I guess? Is there anyway I could somehow get this upgrade? I called QRPC support and they said they can't do it on their end.