Where did the island disappear to? Why can't I go to the island I've already passed?

After completing all the tasks on the story island and upon moving to the next island, you will be notified that you have 24 hours to visit the island you have passed. This time frame is provided so that you can complete everything you started on the island. After the expiration of this time frame, the passed island will be closed and you will not be able to get to it anymore. The countdown to the island closing time begins only if you have moved to the next island.