These tiles certainly can be problematic, main issue I get is with pre sealed or washed over prior to the seal, look dry . They can ghost, whiten give a dusty appearance,patchiness .some will say that this is the look , but they can be installed with crisp / rich colours.
With one of our large suppliers, we cut down replacement by 60% by drying/releasing moisture prior to sealing, there is such a vast range of these tiles on the market with differing density and porosity ,this can offer many options of fixing ,if tested. Floors installed with a crystallising addy would be ideal perhaps ,but double the price perhaps ,Self levalers, screeds not fully dry can all add to the moisture level needing to release through these tiles, if there is an impregnator to barrier this , it can cause issues If you produce a salt within the body of the tile ,this will not be removed easily ,if at all
Gary, would you use a water based over a solvent? These are not so prone to the whitening, discolouration ,they just don't work as well,with moisture present.