Demi Lovato reportedly disappeared from the set of The X Factor during auditions in San Francisco on Monday.

The 19-year-old starlet was appearing alongside Britney Spears, L.A. Reid and Simon Cowell to judge upcoming talent.

But RadarOnline reports that the former Disney star did not return from a judges break and although her seat was empty, the rest of the gang carried on without her.

"All the judges took a break together but when Britney, Simon and L.A. came back there was no sign of Demi," a source told the site. "They just carried on taping without her."

"It was a bit weird and everyone wondered where she'd gone."

This is not the first time that judges have done disappearing acts from set. Britney missed an audition in Kansas and "took a break" missing three auditions during her first day in Texas.

"If someone needs a restroom break, of course the other judges just continue," an insider said adding that Demi later returned. "There's a lot of auditions to get done every day and they don't finish until 10 or 11pm as it is. It's no big deal."