I had the front stoop renovated a few years ago. They put stamped concrete on top of the original stoop and installed these bluestone slabs as steps. I was going to caulk some cracks that I saw before applying a sealer and when I was kneeling on front step it moved. I realized both steps were completely loose so I put them to the side to see what was going on underneath.
Now I like to think I'm pretty handy and I can fix just about anything around the homestead but I never really messed with concrete/stonework much. So I assume I need some sort of adhesive/filler... maybe some sort of epoxy??