beforeUpdate doesn't seem to be called

How are you updating the user? There is a difference between getting an instance of the user and updating it and updating by querying the model. The former is an instance update and the latter a bulk update operation (even if your where filter would return a single item).

This distinction is important because beforeUpdate is an instance hook so it would be triggered on instance updates only. You can either change the way you update the user or implement a beforeBulkUpdate hook as well.