As a dissident, Roy Medvedev was urging a ‘return to Leninism’. That is why he was a dissident that the party was not real concerned with.
He was one of the founders of the Communist Party Of The Russian Federation.
Russia never had a separate Communist Party until 1990.
Solzhenitsyn has some great observations about his internment in The Gulag Archipelago-I just finished reading Katorga this year-and other prisoners that remained committed Marxist-Leninists, even as their government put them into a meat grinder.