Under IATA "rules" (which are simply industry agreements), the other carrier has 72 hours to confirm positive space when a reservation is made. BA may then have as little as 24 hours to ticket.

This seems to be a problem for other major international carriers as these tickets are fetched to the head of the queue without human intervention. It is a BA IT fail that this happens on BA.

While it should not have to be, the real risk is that the space is gone and cannot be reinstated and there are no other good options. Thus, as it rolls up to 72 hours, check with the other carrier(s) and then back with BA.

As others note, BA can, of course, push your ticket ahead of others for ticketing.

Why this should take your time in 2017 is beyond me, but as between not flying your intended route as you had intended and leaving it to software which does not work, the former ought to prevail.