Is she exclusively peeing/pooing in the bath/bathroom floor i.e. is she doing one thing in the litter tray and the other in the bath?

My instinct tells me that she's probably reacting to the change in litter type. Cats can be really picky like that. And they can be really picky to the point of doing one type of elimination but not the other in the new litter. I've been through this too, where I changed litter and my cats would not use it, or use it sometimes and not others, or use it for peeing but not pooing.

Can you see what happens if you go back to clay litter completely? If that fixes the problem then I would slowly start introducing a small amount of crystals into the clay and gradually increase the ratio mix to be more and more crystals over time until she makes the transition fully.

We use crystals too as they last longer and absorb a lot more smell, but it did take some time and the above method to get one of our cats in particular to get used to it.

HTH