To generate Automatic Tasks linked to assets, you should go to Functionalities > Automatic Tasks > +New.
You have to keep in mind that the type of document you must generate to link an asset to a task must belong to the SAT section; work estimate, work order, work delivery note and/or ordinary invoice.
SAT.
When you indicate a customer on the To whom tab, you can link the asset. If the client has more than one, you must keep in mind that the software does not generate one document per asset, but you must register, for that client, as many tasks as assets are available, selecting each asset in a different task.