Apart from the moisture the adhesive used states suitable for anhydrate screeds.....
Not going to get in to a clip debate in this thread, but if that problem occurs due to clips being used, it’s because they’ve been used incorrectly.Back buttering would have helped on tiles that are so big for sure but those levelling clips simply lift the tiles out the adhesive. I used them once and can remember having a problem with the tiles creaking as you walked on the corners as there was insufficient bed in the corners due to the lift of the clips.