After defeating the queen in the first nest, my team of five healed, built missing ammo, had their inventory redone, and went to a second nest. I’ve tried both using the button to attack the nest, and choosing “leave”, then using the button at the bottom of the Geoscape to resummon the dialogue and enter that way, but it breaks the game.
When I choose to enter, the game moves to a loading screen and displays the loading animation forever.
This seems to be for any mission. I cannot enter outpost defense or anything–it goes to the loading screen in the current game. Shame, I started in the UK for that playthrough.
EDIT: I started a new game, and was able to enter missions successfully.