'?admin-key=' argument fails to prevent redirect

I'm using Context Redirect in conjunction with Context Mobile Detect to redirect home page visitors to a mobile version of the home page.

I added an admin key value ('no-redirect') so that we could prevent redirection to mobile on mobile devices, to allow us to test for failure modes on mobile.

However, it doesn't seem to work: adding the querystring '?admin-key=no-redirect' does not prevent redirect on mobile devices.

I tested with 'Attach querystring' both enabled and disabled.