Sometimes pressing <leader> cancels previous <leader>

Describe the bug
Weirdly enough, sometimes pressing double causes vim to think nothing has been pressed. (I see the first leader recognized in the status bar, and then it disappears when I press the leader again.)

To Reproduce
Steps to reproduce the behavior:

1. s a r a (some easy motion)
2. s a r a (again)

The second time, the leaders cancel, and sneak intercepts our keypresses.

Environment (please complete the following information):

• Issue Type: Bug
• Extension Name: vim
• Extension Version: 1.13.1
• OS Version: Darwin x64 19.0.0
• VSCode version: 1.45.0-insider

{
	"messages": [],
	"activationTimes": {
		"codeLoadingTime": 1055,
		"activateCallTime": 2,
		"activateResolvedTime": 208,
		"activationReason": {
			"startup": true,
			"extensionId": {
				"value": "vscodevim.vim",
				"_lower": "vscodevim.vim"
			},
			"activationEvent": "*"
		}
	},
	"runtimeErrors": []
}

No file or test is named in the issue. Start by reproducing the two leader leader s a r a sequences in the VSCode Vim extension and inspect the leader-key handling and interaction with sneak; done means repeated leaders consistently trigger the motion without being cancelled or intercepted.