Trying to utilize Bulk Loader and trigger some tasks (such as "Synchronize User") are not available from the drop down box.
The internal logic on the code level is trying to match the action in the CSV file (ie create/ modify) to the actual relevant tasks available for the managed object in question. So when CSV contains actions such as create or modify, only create and modify type tasks will be available in the drop down box. When there is no match found (ie myAction), it lists all the available tasks for the specific primary object
Identity Manager 14.x
Change the action (on the CSV file itself) from 'create' or 'modify' to a generic name (sync, for example - or custom) for the complete list of tasks to appear