Yup it happens even for audited shared course, no idea why. Just report it. Go to lesson info and then report it.
That Report Button need to placed in a more visible obvious place within the lesson-sentence/page view. Shouldn’t be hidden away.
You can also use edit sentence (in sentence view) to fix timestamp or you can use rooster’s lesson editor if you have tons of time syncs to fix (but it doesn’t work for shared courses.).