When I played with NJ or Anu, I always had the choice between
New Jericho: Project Nemesis
DoA: Liturgy of Divine Flesh
AND Virophage Injector.
Now, playing with Synedrion as allies, I was never given the option to research the Virophage Injector.
But the final mission is given to me because I followed Synedrion to the end, just not the Virophage Injector.
Is it possible, that this happend, because I never raided an alien lair, just the citadels?
The lair is still a quest on geoscape, but all colonies are now citadels for me.
In my last playthrough with Anu I didn`t raid any lair, just citadels too, but that quest vanished somehow.
EDIT - Solved:
It was indeed the lair. Since there were only citadells on the field, I had to conquer a second one, research the “lair”, conquer a 3rd citadell and research it, the I was given the necessary research.
Sorry for the trouble from my side.