Maybe she's not actually captive-bred? Or maybe she was kept in a tub that she couldn't see thru? You might put up a strip of dark colored paper about 5"
wide around the bottom of the tank, so she can't see thru the glass. (you could probably remove it after some time passes & she accepts the boundaries?)

BTW, I've kept many snakes, but not sand boas...this is just my 2 cents. IMO, her behavior is more typical of w/c snakes, but I'm interested to see what
K.S.b.-keepers think?