Shower tray, tile, sliding door and control unit install done recently. Repair work on the enclosure due to a leak. I deal with alot of repairs like this. Usually a bad sealant line or the wall behind the tiles not rigid enough to prevent the tiles, grout , or sealant moving. I focus heavily on making sure this is done correctly when Installing. I like to add a line of silicone behind the tiles on the bottom row where it meets the tray for that extra bit of reassurance.