Hi ohilere imiere,
Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.
Can you try the same process in incognito browser and try to clear cache, logout and relogin in case there is a session already running.
Just a note - The sandbox may only be used to complete training on Microsoft Learn. Use for any other reason is prohibited, and may result in permanent loss of access to the sandbox
You can work around the issue by opening up a new tab and activating sandbox using below link:
Once you have successfully completed the Exercise, accepted permissions, etc., and sandbox is activated, complete the tasks as described in Exercise - Explore the Learn sandbox. Additionally, you may leave the tab open and use the same sandbox for the Exercise - Create an Azure resource later in same module.
If you found it helpful, could you kindly click the “Accept Answer and upvote” on the post.
If you have any further queries, please let us know we are glad to help you.