It seems that the rumor got started that Lupita Nyong’o was unable to film her motion capture scenes due to other acting commitments that she had.
At the same time, we’re sure that Lupita Nyong’o probably has a contract with Lucasfilm that lasts through Star Wars: Episode IX at least, assuming the character makes it that far.
If she didn’t do it, we’d be writing about the lawsuit right now.
Showing up to film her scenes isn’t really an option.