This is a know bug on Audioshakes side that happens rarely.
There have been instances where the lyrics seem to become increasingly delayed towards the end of the song, as if they're following a slightly slower tempo than the song itself. This is an unfortunate bug that has been around for as long as we've been using the Audioshake AI widget, and we still don't know what causes it. It is not even possible to circumvent it by starting a fresh project with a new job ID, since after having run a few tests we have concluded that the problem will carry over to all subsequent projects as well. Your best bet is to manually adjust the lyrics whenever they start to look noticeably late. Thankfully, selecting and dragging several lines at a time is usually enough.
Whenever you encounter this issue, please write a comment on the task manager so that we'll have more reference data.