particular Podcast (ct uplink) not playing

Hi there,
I like using my Squeezebox setup (LMS 7.9 running on Debian server, squeezelite running on multiple raspberry pys) to listen to podcast.

This works just fine with all but on podcast feed. I just can't seem to get this one to play (multiple urls which all work fine when tried manually and also working on the android app pocket casts):

http://blog.ct.de/ctuplink/ctuplink.rss
http://heise.de/ct/uplink/ctuplink.rss
http://download.heise.de/ct/podcast/ctuplink.rss

Does anybody have an idea how I can get this thing to work?

Thanks in advance
Zurrel