Currently, you can only add tags to the 'Preserved Tags' list from the context menu one by one. If you select multiple tag fields (e.g. Title + Artist + Album), the option will be missing from the context menu. It would be handy if you could also select multiple fields and add them all to the list in one go

Edit: Same goes for "Remove from 'Preserved Tags' list" if you select multiple tag fields which are already on the list.