The only story I could find was an accusation of sexual abuse of a 12 year old girl in 1965 in New York, with the accusation coming from a woman in 2021. The original accusation could not be true because Bob was not in New York at the time, but in the UK. Later the accusation was changed and still later, in 2022, fully dropped; no evidence was ever given.

If you have a different case in mind, I would love to see some sources, because I can’t find anything else.