The thing is that the return legs (on BA for the longhaul and EI ex-Gatwick) are the ones which are missing from MMB. It appears as a one-way trip at the moment!
The outbound on BA/AA are fine. I have my e-ticket receipt with details of all the flights, so it should pan out okay, but I'm slightly concerned in case my seat allocations will have disappeared too.
Will call BA tomorrow if it's still messed up.