Selecting records while you have groupings, will only select the records of the groupings that have been expanded and that is currently displayed on the page. Varibill does not allow the selection of records that are not being displayed. This allows you to select multiple records across groups, without selecting all records of collapsed groups. This also prevents you from deleting incorrect records. Varibill further more does not allow the deletion of records linked to other entities. e.g. a product with a selling price cannot be deleted until the selling price has also been deleted. This is to ensure the integrity of your data.
For more information on the basic functionality of Varibill, refer to docs.varibill.com.