75 Power Genestealer Cult (Darren) vs Joe

First three Genestealer battles:

Power 75 Mission: The Scouring - Genestealer loss, Tyranids (Joe) Win
Power 75 Mission: Big Guns Never Tire - Genestealer loss, Grey Knights (Joe) Win
BUT
When I created a Tyranid list for Joe to use:-
Power 75 Mission: Secure and Control - Genestealer Win, Tyranid (Joe) loss