Morning, Can someone tell by looking at these images why the tiles have loosened. Laid on floorboards with 12mm Hardie screwed down on a bed of cement based adhesive. I'm confident floor itself is sound. Tiles are 300 x 500mm ceramic wall/floor and laid using slow set adhesive. It seemed to take ages for adhesive to go off - well over 24 hrs. Remaining tiles seem ok no hollow sound. But I think they would be easy to lift.