A cloud-based task management app from Microsoft that helps users organize and manage daily tasks across devices.
Dear Pratiksha Rathore,
Good day. Thank you for posting to Microsoft Community.
As per your description, you want to check the task details when it completed, but when you mark it as completed, it disappeared.
Based on my test, when you mark a task as completed, it is automatically filtered out. You need to click “Clear all” on the right corner of the page, and select the completed task and choose “More Options” > “Open Details”
Let me know if you have any question. Thank you for your time and patience.
Sincerely,
Claire | Microsoft Community Moderator