This has now been fixed and the patch is on GitHub here:
https://github.com/EpicGames/UnrealEngine/commit/c53639c36c108d93fd816ed8afdfaa437b400556
I should also add that you could use Emplace to add your tuple to an array, which is both shorter, more efficient and works on TArray today:
cont.Emplace(1.0f,0);
Steve