The search seems to be glitchy at the moment.

I've booked three return trips online in the past few years (LHR-HND x3 and HND-LHRx3, all in March/April or October) and I failed to get business seats on the date that I wanted for the first time last week because a search started at midnight didn't show any availability.

The same thing happened the following day but I was expecting it and (when the seats didn't appear) I immediately repeated the search by clicking 'Change'. The seats then appeared and I made it to the 'creating your reservation' screen at about 45-50 seconds after midnight.

(For what it's worth I'm not sure how true it is that phone agents can lock down seats at the stroke of midnight - every time I've seen availability, I've got the seats. But perhaps literally only one or two people bother phoning on any given day and they might be content with PE, particular for a day flight.)