I only own a gasteria, so I have limited knowledge. I would say it's getting too much or too little water. What kind of sunlight is it getting? I see there are blinds in the picture...are they opened regularly? My succulent gets bright indirect light and is happy with that. When I do water it, I don't soak the whole thing. It gets enough enough drips to satisfy it. I try to imagine when it would get in its natural habitat.
Sometimes you just have to play around and see what works. I will keep my fingers crossed for you!