SBorder::SetContent() VAlign Fill

I’m building UI in C++ and I’m running into an issue where I can’t get the contents of an SBorder to fill the size of the SBorder. I have the SBorder and call SetContent with as SVerticalBox that I then add list items to. I want to push the last two items down to the bottom so I add a spacer. The spacer doesn’t do anything because the SVerticalBox doesn’t fill the SBorder. Here’s my code:

Border = SNew(SBorder);
Border->SetPadding(FMargin(0.0f, 20.0f));
Border->SetHAlign(EHorizontalAlignment::HAlign_Fill);
Border->SetVAlign(EVerticalAlignment::VAlign_Fill);

List = SNew(SVerticalBox);
Border->SetContent(List.ToSharedRef());

But there’s no option to set the alignment of the content so I can’t set it to fill the SBorder.