Global Talent is valued partly because it is not tied to a sponsoring employer. That flexibility should not be confused with complete independence from the endorsement that made the original grant possible.
For a person who entered the route through endorsement, the Immigration Rules require the endorsement not to have been withdrawn at settlement. A problem arising shortly before the application can therefore affect a carefully planned 3 or 5 year route even where the applicant's work and residence history are otherwise strong.