^ Me too. Was desperately trying to book a redemption flight on the LHR-DXB route for ages (almost a week). The search never worked for me.

Ended up booking a paid flight on Emirates for not much more than the cost of the additional taxes you pay on a BA redemption flight. Got exactly my dates, convenient outbound and return times and got my seats reserved. Saved myself 40,000 almost useless Avios.

Ironically, I used up my remaining BA Avios on a hotel booking in DXB. Goodbye BA, and good riddance.