But Darlington assistant manager Atkinson told the Evening Chronicle: "Sessegnon has been a massive plus.
"The games I have seen this year, I have been really impressed with him. Whether or not he was unhappy before, he looked a different player towards the end of the season.
"He is the sort of player you hope Sunderland can keep a hold of.
"He can change games and has done. He is a quality player."