Any one out there had or are having a problem with soft grout. Grouted a bathroom (walls) with 15 x 7.5 crackle ceramic tiles. Sealed the tiles and once dry grouted tiles. Everything fine, popped back the next day to buff up the tiles. Customer informs me he sprayed a grout protector on a few days later. Few day after that the shower was fitted and used. Customer calls me to inform me the grout goes soft and start rubbing out with a cloth when wet. Hardens when dry again. ANY IDEAS? and is there a product i can put on the grout when dry to waterproof them?our tiling question? Pictures can be added.