Can you post a photo?

What size is your plant?

When you unpot did you see any new feeder roots?

In general they like soil warm and moist with full sun.

They look so much like Fokea edulis on steroids..and that's where my 2 cents comes in. The only time my E.edulis had a similar growth drought is when i re potted it into a mix too heavy in sand. After months of waiting to see if it would snap out of it,i just took it out of that pot..where some of the rootball fell away..then replanted into a mix with more than half perlite. Recovery has been slow but steady.
In reading what little is out there on that plant it also seems to be a cut more tender than most succulents grown outdoors in California,even Southern Cal.
You might try as hot as possible-but no direct sun on that great caudex...that might be more sensitive to hot sun than the viney top growth...as per F.edulis-and the also similar Ademia.

I'm gonna try posting a photo until I get it on here (please excuse mess). It shows the elephant dropping pulled from substrate laying across a fockea edulis kept same way growing. Off to left you can see a pathetic rootlette. I scraped caudex w/razorblade just now after unpotting revealing potato-color, not green like I remember when scraping higher up. I've had this thing easily over 115F before, that's enough if heat is what it wanted. Here in Los Angeles the task is to prevent the greenhouse from becoming an oven.

{{gwi:605976}}

The top of the knob feels woody whereas the attachment to caudex is more flexible. I've cut leggy lithops down, sunned them and had them divide into beautiful multi-headed plants before and am wondering if the knob might be dead and I might encourage vining below if it were removed - and in removing whether I should expect to see a green layer on a healthy plant or am I hallucinating and they just look like potatoes. I don't use perlite and do have sand in there and don't have immediate intellectual recall on what advantages perlite is intended to provide? Thanks.

If it looks like a potato I think it's goner, should be green when scraped.

Sand compacts, doesn't drain completely and does not provide aeration for the roots. Perlite increases aeration, drainage and doesn't compact.

Just did more scrapings and find that the below-ground part looks potato-ey but the above-ground part even that which I'd suspected was dead is actually very green. Looking at your substrate instructions and advice not to burn caudex, I'm thinking I'll repot again and try treating it like a Hoya - super-hot no direct light fluffy draining soil/media regularly remoistened. Thanks again.