Automatic Litterbox Central

We've got a new litter robot AND new cats.
Like always, cats needs to be introduced with their litterbox, so I let them out near the litter robot. One cat just sniffed a bit and then crawled into the robot. It's now her safe place and she's been there since a week. Kick her out, and she's back into the next minute....

I've just disabled the robot for now....

Now what? Any idea how to not have the robot be a safe haven?