Problem with certain podcast rss feeds

I’m trying to set up a Musicbox implementation on a Raspberry Pi 3B+. I have a problem trying to access the podcast “99% Invisible” which uses one of two rss feeds:

For some reason, my musicbox refuses to see the episode lists provided by the rss links. Other podcasts, such as NPR or Radio Lab seem to work fine. Even the BBC. But not 99%. Uses those links in the podcast playlist for VLC (on a Fedora desktop) works just fine. Is there something obvious I’m missing?

Tanks vermillion,