A somewhat awkward workaround by use of Section feature of List elements:
Select every column in List element, copy and paste into same List so you have two of each column.
Create a Section by selecting one of each column header in the List element, then click the Section button.
Unlock the formatting (padlock icon) and remove all the text items from inside the Section header. Then add a block element to the inside of the Section header (can apply Size and Formatting properties here if desired) and optionally remove the "Section Header Cell" Class of the Section List Cell to remove the line separator.
Set column titles as hidden in the bottom List element properties (you can hard-code column titles with a Table element if needed).
Voila! Blank lines in-between each row in your list element.