We selected these planks on the recommendation of the flooring company our builder used. The builder put down a plywood sub-floor between the new concrete slab and the vinyl flooring. Soon after moving in we noticed gaps between the planks forming everywhere. Installers have been and gone many times, trying to glue down the planks again. Eventually Karndean sent a rep out and they took a plank away for testing. After much time they went ahead and replaced all of the flooring. They acclimatised the planks for 48 hours then installed again. The install looked like the brochure, all the planks butted together nicely... but not for long. The gaps are happening again, all over the place as per attached photos, and what once looked like a nice install looks terrible again. Is this likely a problem with the planks? Could it be a problem with the sub floor shrinking or expanding? I've measured the planks where the gaps are and they seem to be the correct length. Very frustraing, and of course between the builder, the installer and the manufacturer no-one will take responsibility or be honest about what they think is causing it.