I learned something about this with my degus - I bought them a massive rabbit run for free time. They hated it, just stayed in their hides. Then I used cardboard to line the mesh sides & they were totally different, exploring all over. I think a lot of prey animals hate being exposed from all sides & will mostly hide. It's genetically hardwired into them so I'd work on making them feel less exposed, see if that helps.
You could try a more enclosed area by using cardboard boxes or use tunnels (I like Boredom Breaker ones) - In a average size room I'd probably use 4 tunnels & 5-6 big boxes as well as their huts/houses. Make sure they're kinda linked together so there's no scary expanse of open area.