If I check the streams with the Radio Curator’s stream tester Roon plays them OK. This should mirror the Roon app. However, in the real Roon app, the streams produce a 401 (unauthorised) error. I can see nothing wrong with the streams.
Hello again. Those referenced non-https links are effectively the same as Roon uses, although Roon uses them via .m3u links, and so things should (and usually do) work.
In this case, there is a bug in Roon where it is apparently not dealing with the redirections correctly.
I have replaced the URLs with working links and will inform the Roon devs.