Hi there!
I don't think you are doing anything wrong in this situation. You have to remember you've only had her a week, whilst she's gotten used to her old routine for the past eight months (which is a very long time for a hamster).
I would wait it out for a short while and see if she may eventually pick a hide out for herself. As long as they seem to be acting fine. However if she keeps sleeping in the same spot I would suggest perhaps moving their wheel and sand bath and placing a hide in that location. Or simply separating the wheel and the sand bath. Sometimes a change is all it takes for them to get going.
But I would still let them get used to their surroundings first. They have had two major changes in recent times so it may just be stress.
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