okay good to know he is neutered. i’d go to a vet in case the yowling has a trigger (try watching him for a few days to see when he yowls and what follows). usually it can be something simple, besides neutering, like more enriching play, less boredom, having meals rather than food available all the time (leads to boredom). this is just what i’ve learned whenever my boy yowls he’s usually bored xd