Are cross bred rabbits sterile?

I am just wondering if cross bred rabbits are sterile. I have 2 lion lops (Lion head X Mini Lop) they are a buck and a doe. I just need to know if they can reproduce, if so i need to get another cage to separate them. I know that Mules are sterile and crossed between a horse and a donkey. So i figured that since these rabbits are cross bred that they would be sterile too. I just need to know that you very much for your time.