The Tasks tab on the Action Items table is privilege-based. 

To see the Task tab within the Action Items table, the user must have either Create Task, View Task Page, Edit All Tasks, and/or View all System Tasks privilege(s). If the user does not have one of these privileges, they will not see the Task tab on the Action Items table even if assigned to a pending task.

Note: To add, remove, or modify privileges please contact the User Admin for your organization.