In my experience, it's not unusual for robos to hide. This is especially normal in your case, as your ham is still very new. I'd give her a few more weeks to settle before being concerned. Add more cover in the cage- this includes, tunnels, nests, toilet tubes, and huts. This cover may encourage her to come out a bit more often
Just wanted to note that some hams are a bit reclusive. My robo almost never comes out. I, like you, stayed up very late into the night in hopes of spotting her, but to no avail. I've just left her alone, and as long as she's happy and healthy, then I'm just fine with it
