Regarding your request, without the possibility of a live inspection, I can only make conjectures and hypotheses.
1) The cracks on the terraceare hardly ever due to poor tile quality. Often their development is due to a bad laying, which did not consider the dilatations and the structural movements that can be made by a terrace, exposed to -10 ° in winter and to +60/70 ° on the surface in summer. If the tiles have cracks or fissures that pass from one to the other, my diagnosis is more than a hypothesis.
2) You can use the highest quality and thickest tiles on the market, but if no expansion joints have been made, if a flexible and elastic glue has not been used to balance structural movements, if no installation has been made with double layer of glue, if no suitable waterproofing has been made, etc… your terrace will necessarily have defects. If only one of these things has not been done, the tiles will jump, crack and come off.
Please also note that all terraces are always at risk. In fact, abroad they no longer perform glued floors; they cover all the terraces with floating floors, which, at any time, allow you to go and restore any loss of waterproofing, without removing anything.