I've been burned by BOTH of these gift card issues. I had two AUS-BCN tickets on hold, SWUs applied and everything, and then was told I couldn't use gift cards when ticketing. Decided to gamble and lost a C seat on my preferred routing (through MAD) but was able to score one through LHR.

AND, I often book tickets ex-DXB (J fares ex-DXB are pretty low), and hate not being able to use gift cards on those.

What a pain.