I have added the AWS Level 1 tasks for practice but I am unable to open the task and also the Start option is not visible.
You might be having a few incomplete/failed tasks in one of the other Domains you’ve selected in your Active Practice page.
Try replaceing them with the Domain that does not have any incomplete/failed tasks, and that should resolve the issue.
I did but still not visible the start option. The start option is visible to Jenkins task.