Originally Posted by
BA or bust
This might be a way off suggestion, but if you have just booked them and they not ticketed yet, that might affect your ability to select seats perhaps.
One is new , one isn't ... but yes good theory

.. but I think it's a more general issue
Both are BA Holidays bookings .. tickets have been issued with 125-xxx numbers ... The page on BA.com before you get sent to IB.com gives the usual BA 6 character alpha numeric locator and also gives an IB 5 character alphabetic only PNR which then doesn't seem to work on IB.com ( nor does the original BA PNR or the BA eticket number )