Given the back story this would appear to be a ticket which has quite an extensive history. Many (most?) people can get the disruption menu to work thanks to having a simple booking, but at a certain point some tickets just need a manual rebuild. Ticketing infrastructure dates back to the 1960s and though they are often called e-tickets, the actual design is based upon paper tickets. Until quite recently all rebooking had to be done by contact centre staff, now MMB does give some options for self resolution in many cases, but cases like the OP are going to need a phone call to resolve. Unfortunately when BA cancels lots of flights this then leads to contact centres being overloaded, often with people just checking details which are available online. There isn't an easy answer - or rather those easy answers involved removing all the complexities that are so loved in this forum - companion vouchers, open jaws, complex redemptions, UuA, POUGs, AUPs, a long long list.