Sorry mate this is my fault. It's a really old thread and without a doubt sorted now. I've been pulling up some of the older longish threads the past few days.I would have a guess it was the old matting and the fleece has come away from the plastic, it happened to me on a few jobs. Dural came out drilled holes in grout and injected with resin it solved the problem.
Dural were also supplying porcelanosa with it but blue and l had a couple of failures aswell. The dural rep said we have stopped repairing now. As we have over a million m2s to fix and it will bankrupt us. Hence porcelanosa have designed there own and it's awesome no where in the make up of it to fail. I only use that or kerrakol hydro build.