“Who said the two sides arent talking?”
Zelensky.
The two sides are not talking in public.
Actually they are talking on several levels, because they keep arranging for, say, prisoner exchanges. And I suspect there was a quid pro quo that arranged the lack of Ukrainian interference with the withrawal from Kherson. They were after all within easy artillery range of the crossing points. I dont know what the Russians traded for their men. Possibly a promise not to blow the Nova Kakhovka dam, who knows.
Its like the allies and the axis in WW2. There were always backdoor contacts between them. Of course they had nothing substantial to talk about until the Germans (generally locally in fact, each army/army group separately) decided to ask for terms.