The 40-year-old R&B singer and The Weeknd performed his single "In the Night" on NBC's The Tonight Show Starring Jimmy Fallon. Her appearance was a surprise—The Weeknd, 26, introduced her one minute and 40 seconds into his set.
"Most important experience of my life. Thank you Ms. Hill," The Weeknd tweeted.
Recording Academy President Neil Portnow told USA Today after the Grammys the two were expected to perform the song together at the ceremony, calling her absence a "disappointment." The Weeknd ended up performing the track alone.
Her rep had said Grammys organizers "announced a performance by Ms. Lauryn Hill prematurely and without approval."
"Ms. Hill had concerts all weekend, leaving no time to prepare, and was uncertain she would even be able to make it to L.A. in time to rehearse for the event," the rep said in a statement to E! News. "Any performance that could have happened was never confirmed, and should not have been advertised as such."
"Ms. Hill was invited to do a collaboration with an artist she appreciates," the statement added. "The performance was intended to be a surprise and unfortunately due to its last minute nature, was unable to come to fruition."
Portnow told USA Today, "None of that statement is accurate."
He said Hill took part in a dress rehearsal Monday morning and then left the building. A fan photo appearing to show Hill rehearsing with The Weeknd surfaced online hours before Monday's ceremony.
"Our intention was, and we were ready, right up to the moment of the performance, for her to step up on stage," Portnow said.
Rolling Stone later quoted her rep as saying in response that there were "official Grammy television ads that ran for a couple of days naming Ms. Hill as a performer on the show" and that "her camp was unhappy about this." CBS, which aired the Grammys, has not commented.
"The performance was also supposed to be a surprise. This was discussed with Grammy organizers, and the TV spots were pulled," the rep said. "As previously mentioned, Ms. Hill attempted a last minute rush to LA, to see if this could happen, but unfortunately timing that day kept it from being a reality. Ms. Hill truly appreciated the invitation, and the efforts made by all parties to try and make the performance happen."
Hill is meanwhile preparing to go on tour next month. Her Tonight Show performance marked her first TV appearance in almost six months. Fallon's current and past series are the only talk shows where she has given a performance in more than 15 years.
(E! and NBC are part of the NBCUniversal family.)