Her hides don't sound right to me: toilet paper rolls are open at each end & don't offer a snug feel to such a small snake. I think your snake is still too
stressed after being at the store, & still cannot relax & feel safe...that's why she burrows into the substrate.

Is her cage in a quiet location, without a lot of human or other pet activity? without tv & music (they feel bass notes very well as vibrations) or doors slamming?

Are you feeding her only at night, in dim or no lighting? Have you been handling her at all? No handling of a new snake is best until they feed 3+ times easily
for you at regular intervals; I know how tempting it is, also that for some snakes it won't matter...but for many, it does. They need to be "snakes" first, so the
feeding instincts get well-established...nature did not design them to be domestic pets.

Have you talked with the person you got her from? They might have other suggestions to offer.