When new or edited task types are added into AppColl, we do not apply those changes retroactively. For example, a new task type is created called "Send Reporting Letter to Client" and triggers when a matter issues. This task is not auto-created for existing issued matters. It only applies moving forward. This is done on purpose to prevent rampant task generation if the task does not work as expected. However, you can regenerate tasks to apply these changed retroactively.
There are two ways to regenerate tasks which depends on what the triggers are. You can regenerate tasks at the task level and the matter level. For the above example, you would regenerate tasks at the matter level since the triggers are based on a matter's status. Additionally, you can regenerate tasks at the task level. For example, creating a reporting letter task when an office action is received. This would be used if the new task type auto-generates when something happens to a task and not the matter as a whole.
The below video the explains the process in detail.