So, retiling my shower. We've applied waterproof membrane and everything was looking great, until it came to tiling. When we started, we noticed in one place it was blistering away from the wall, although not too much so we thought as we were using large tiles it wouldn't be too problematic. Turns out the tiles looked a bit of a mess and were 'squishy', so we pulled them off ( they'd only been up about 5 minutes) to find a large section of the waterproof membrane came away from the wall with it.
My assumption here is that maybe the glue underneath hasn't dried properly despite the fact it was left for a couple days. How do I remedy this? Both the glue not drying and the fact that we've now got a massive section where the membrane isn't fully attached to the wall.