Despite not having formally asked to leave, Ndoye has reportedly agreed to personal terms with Napoli, who are also interested in signing him.
Nottingham Forest may reattempt to acquire Ndoye as they seek a replacement for Anthony Elanga, who joined Newcastle United earlier in the season.
Last season, Ndoye played a key role in Bologna's Coppa Italia win, scoring nine goals and providing six assists in 41 games.