Tiles Keep Cracking

[Tile Shop]

How big is the area?
How long did you have the tiles before they were fixed and where were they stored?
Have you left a perimeter joint or used any expansion strips?

 

[RP13]

Hello mate biggest area is 7mx3.6 I left a perimeter gap but no expansion joint. I had the tiles 2-3 months prior to fitting and they were stored in the living room area ( the only room not tiled)

 

[hmtiling]

Ufh and Stone, uncoupling membrane or I walk.
I'm not up on these anhydride screeds, but should they crack like that? I've only seen one other one and that had cracks all over, so walked away.

There's only one company that do them here and they crack more often than they don't.