Many of the Lithops are not behaving according to the rules this year. Quite a few still haven't completed shedding their old skins at this late stage and others just haven't bothered at all.
This is a case in point.
The only new growth is the small head between the two large lower ones. This formed from the bottom right head and emerged from a two year old half head ( see above). Last year I believe I watered this plant once so I don't think overwatering can be a contributing factor.
I have therefore decided to ditch the rulebook and do my own thing, something you may think I normally do anyway and you wouldn't be far wrong.
On the bottom left head you can still see half the head it formed in 2019 still not completely dried up.
Lithops are amazingly adapted to doing absolutely nothing when it suits them