I have also had this issue, grouted an entire bathroom including a fair amount of mosaics, only to find that the gout wouldn't stop bleading. I had a section in another room to do so I decided to see if I could get it to work. No luck, didn't matter if I did a wet mix, standard mix, dry mix, and it didn't matter how I cleaned off the excess with a sponge, wet or dry, it always ended up the same. I've been to Topps to complain but they are quite dismissive, insisting bal make the best grout and if there was a bad batch then they'd know about it. Clearly wanting to blame me. I've been waiting a week for them to visit my customers house to view it but they are obviously in no rush. In the meantime I decided to try the plastic covering technique round the shower so at least the customer could use it. I had no other real option as removing the grout from the mosaics would be unbelievably time consuming. Surprisingly enough it's seemed to work. I've saturated the grout with water from a spray bottle then covered with clingfilm, after its dried I took the clingfilm off and wiped it down with a wet sponge then repeated 5-6 times. Very time consuming but not as much as replacing the grout, especially considering I've already siliconed half the bathroom. For anyone else who has this problem try this on a small patch to see if it'll work, it's worth a shot.