The 21-year-old was close to a return after tearing his hamstring while playing for France at the European Under-21s Championship in June.
But Olise has re-injured his hamstring and will have to wait to return to action.
The setback is a major blow for Palace, who will continue to assess Olise over the coming days as they plot a new timeline for his return.
Olise will likely miss Palace’s matches before the October international break, at home to Fulham and Nottingham Forest, and away at Manchester United in the Premier League and Carabao Cup.
Olise signed a new four-year contract this summer, having been named Palace players’ player of the season after a club-record 11 assists last season.
His new deal has a release clause active in it from next summer, after Chelsea attempted sign him for around £35million at the end of the summer transfer window.