Finally received a reply from support. I guess the nexrad radars are considered obsolete, old, and are now unsupported. They want to push that clunky Wundermap that I have used one time.
> AUG 16, 2019 | 11:24AM EDT
> VICTORIA replied:
>
> Chris, this URL is to an old, unsupported product. It's not likely to
> be made to work again.
>
> You might try looking at Wundermap instead. Thank you for using
> Weather Underground!
>
> --Victoria