The South Korean international started the first two Premier League games of the campaign but has had to settle for a place on the bench since – and he was an unused substitute against Villa at the weekend.
Hwang struggled in the Carabao Cup at Brighton last week and O’Neil has acknowledged the dip in form for a player who scored 10 Premier League goals before the turn of the year last season.
“We’re trying everything with him every day to help him,” O’Neil said.
“It’s no secret that he’s not hit the form that he had before, which does happen.