Another commenter said: "The two gas giants orbit their host star at distances of 160 and about 320 times the Earth-Sun distance."

Just a guess but perhaps being in the Goldilocks zone the planets are harder to discern from Alpha Centauri.

I figure the technology that blocks the star light may mean this isn't the case though.

A comment upthread mentions that one of the biggest obstacles to detecting planets is the huge contrast between the planet and its host star: detecting 10-14 orders of magnitude difference between the luminosity of a star and orbiting planet cannot be made simpler by adding in 2 additional stars.