Originally Posted by LeisureFirst

It is extremely common for MMB to have options greyed out for things that can actually be done. MMB has limited functionality and you often just have to call.

For example, when I book a paid CW ticket, the option "upgrade with miles" is usually greyed out, even though it is possible to do this.

Another recent example for me is an F redemption where the "change date/time of travel" option was greyed out. I'm fairly sure this was because of a manual intervention that had occurred by phone, because I'd upgraded this from a CW redemption (without wanting to cancel the ticket and start again). Similarly, when I booked an MFU by phone (it was one that ba.com couldn't cope with) a lot of options and info in MMB weren't right.