Unable to rebind keys to `<S-Up>`/`<S-Down>`

Describe the bug
I am unable to assign a different keymap to } or {

To Reproduce
Steps to reproduce the behavior:

Go to Settings.json and add the following:

"vim.normalModeKeyBindingsNonRecursive": 
[
    {
      "before": ["}"],
      "after": ["<S-up>"] 
    },
    {
      "before": ["{"],
      "after": ["<S-down>"] 
    },
]

Expected behavior
I would expect the } and { keys to be remapped to shift+up and shift+down, respectively. This means that when I press shift+up for example, while in normal mode I would expect the cursor to jump to the line above the previous text block.

Environment (please complete the following information):

• Extension (VsCodeVim) version:
• VSCode version: 1.17.1
• OS: Windows 10.0.19041 build 19041