My bunnies won’t come out of their pen when they’re let out

I have two bonded bunnies, male and female, and recently we set up a large pen for them. They have a pretty large setup, and we let them out frequently, but lately they roam the room very little.

My mom is worried they aren’t happy, but they’re cuddling and laying around a lot. I honestly feel like they’re happy, but I want to help my mom feel better.

Bunny tax, Californian is the female(cinnabun), albino lionhead is the male(strudel)