Trainz Plus "Release Candidate" 103221 (PC) and 103219 (Mac) are now available

Things are moving ahead: I resume a saved driver session, I drive my train, I don't use the train tab, exit and am prompted to save the driver session, everything's OK. Same on two different routes. Then on a third one, still starting from a saved driver session, and still without using the train tab, when I exit I am prompted to create a new session or overwrite the existing one. What the...?