It downloads XML file for me. If you want RSS in Firefox, you need an extension, for instance Brief.

Thanks for your response but that doesn't solve the problem I'm having. While it did after installing, show the feed, it still doesn't work for my extensions in Joomla (and yes, I've got some queries out in their support too in addition to the GWP.)

Besides, there are other sites that use a feed sub that return correctly: https://pjmedia.com/feed

So again, thanks but I'll have to keep looking

I see what you're saying now and I didn't notice it before. It does download the file (looking in my downloads and seeing all the random assigned files) but it doesn't attach an extension to the file. Probably something I'll have to take up with the site creator.

Thanks again for your insight.

I use RSSPreview to preview RSS Feeds in Firefox. It shows this one fine. You could then right-click and View Page Source to see the XML. You can also use Pretty XML to view the XML code directly with a decent interface.