UPDATE: Megan's rep confirmed that she and Brian are engaged.
PREVIOUSLY: Megan Fox and Brian Austin Green are engaged again, Us Weekly reports.
Her on-again-off-again boyfriend proposed on the beach at the Four Seasons Hualalai hotel on the Big Island in Hawaii, sources tell Us, but Megan lost the ring in the sand.
"I saw her jumping up and down," a witness said. "Later, I saw a half dozen staff sifting through the sand."
The search was reportedly unsuccessful.
"Security and maintenance staff spent a couple of hours looking for it," another source told Us. "No one found it."
Megan and Brian began dating in 2004. They were engaged from 2007 to 2009 and rekindled their relationship last year.