Reward Flight availability never showing flights

So i'm just doing some research to see how much a London - Singapore flight would cost me with a business companion voucher. However I thought availability was 355 days ahead of now, but the only availability showing is over the next couple of months, nothing at all after that. Fine, but then when I click on the available dates shown, when I go to the next stage the website says there isn't any availability on those dates?! It even shows on the tabs any days around it that has availability and when you click on the tab it again shows no availability?! Am I missing something, is the website just lying to me (again)