It's time to be clear. So-called cat problems are nothing of the kind. True, they may be problems for humans: but they are not problems for us.
It's natural and sensible for a sensitive cat to stop using a tiny litter tray, or a litter tray filled with the wrong kind of litter, or a tiny tray which we cannot dig properly. Or a tray with such a mean amount of litter that we scrape our claws against the plastic.
I mean, what do they expect us to do?
Would they like a lavatory full of poop and pee? Or one that they could not flush (the human equivalent of digging)? Or one that didn't flush enough water? Would they like a toilet so small that their bottoms spread over the side?
Come off it, humans. It's time for you to take responsibility. What do we want?
Large litter trays, familiar litter, enough of it so we can dig properly, and cleaning. Yes, cleaning, cleaning, cleaning. At least twice a day.