3 months back I uploaded more than 600 queue items on queue. Now some queue items are not visible on queue. Why its happened and how I will get those invisible queue item
To be able to assist, we need more details. What state were these queue items in? New?
You need to review the queue retention policy if it is set to archive you should at least have the archived items in the form of CSV, unfortunately, you can’t just import these into the orchestrator again but you can write a small automation to read the CSV and add each row into the queue.
Should you be using the orchestrator on-prem, you can access the deleted queue’s on the database otherwise you can try log a call with UiPath support to see if they can possibly recover your queue items for you.