[cypher]

You haven't had them long yet so don't despair!
I do find that most of my hams have gone through an initial few days to a week when everything is new & exciting so they are out & about exploring & scent marking everything then they get a bit more settled & go through a bit of a quiet more reclusive stage but gradually become more confident & start to come out more.
For now I would be sure to sit by the tank & talk to them quietly even while they're hiding away so they really get comfortable with the sound of your voice, you could try gently rustling the substrate & scattering a few treats for them so they can learn to associate that sound & your presence with nice things, maybe feed them at that time too.
If they do come out just sit & talk to them at first until they seem comfortable being out with you around then move on to putting your hand flat in the tank, it takes patience as you do need to just keep your hand still for some time, it can take several attempts but they should get curious enough to come to you with time then you can move on from there.
Good luck with them, robos that haven't been handled from a young age aren't the easiest to tame so it does generally take time & patience.