Originally Posted by Hannibal Lecter

This is very common, neither ba.com nor Iberia.com will show you all combinations,
even worse if you'd try with 3 segments eg. MAN-LHR-MAD-ALC.
You'll have to book over the phone and tell them which flights you want,
check availability on each segment yourself.

You are aware that 8 March is one of the announced strike dates?
(February 18 to 22, March 4 to 8 and March 18 to 22.)