This behavior has something to do with how Ragic determines if a subtable row should be saved to the database.
For a subtable row to be saved to the database, it needs to have at least one non-empty values for a row. However, there are some exceptions that we need to consider. For example, if a field is configured to have a default value, its value is auto generated or generated by formulas, it will always have a value, regardless of the rest of the row being filled out or not. Therefore, Ragic has a rule in place to prevent empty rows to be generated. Fields in the subtable row with default values, formulas, or auto generated fields will need another fields' value filled in the same subtable row, so that this subtable row is saved to the database. Otherwise the default, formulas result, or auto generated value will not be counted as a non-empty field.