To add a document to the missing task, you need to access the checklist for this transaction. From your checklist page, click the Action button at the top of the screen and select Add task.

Then enter the required data and, if needed, check the box for the document to be attached.

You can assign checklist tasks to users who have access to the transaction. See the list of opted-in users on the Users & contacts page under the ASSETS section. When the agent is removed from the transaction, their tasks will be automatically re-assigned to the transaction owner.

If that's the case, you must assign the task to the transaction owner. Keep in mind that changing the transaction owner will also re-assign these tasks to the new transaction owner.