I didn’t know there was a rumored flashback scene. I know a lot of people were needlessly freaking out about the idea of one (waah, it’s not Star Wars with flashbacks!) because Carrie’s daughter was cast, and people assumed she would play young Leia. Since we’ve seen her in a shot with Leia, it’s obviously not the case.
Maybe that’s my confusion. I thought a site was reporting a flashback a year ago, but it could have just been speculation after Fisher’s daughter was confirmed to be involved. She may not even have any speaking lines.