The Xtra Factor host said that although there is "a lot of concern" for Hance, there could be numerous simple explanations for why producers had been unable to contact him this weekend.
Speaking on today's (September 17) edition of This Morning, Flack explained: "There is a lot of concern for Robbie...but it's not a big massive manhunt.
"The producers got in touch with him last week, they did speak to him and they just couldn't get hold of him over the weekend to tell him his audition was on.
"This isn't a case that he's completely gone missing, it's just a case of that they could not get hold of him.
"So it could be a case of that he just didn't have his phone or maybe he hasn't got a phone at the minute...they still haven't got hold of him, but I'm sure he's okay, they just want to hear from him."
On Hance's progress through The X Factor, Flack continued: "He does make it to Boot Camp and there's a massive story with him next week which obviously everyone will see."
Hance made his X Factor debut on last night's (September 16) episode singing 'Coconut Skins' by Damien Rice.