When you export a playlist, any local files contained in that playlist will be copied. An M3U playlist file will also be created."
Nope. I get music files only.
I’ve made sure that the files are mine, and that they all reside in the same folder.
A secondary issue is that mounted volumes do not appear in the Export dialog. I have to use Volumes, despite the warning that Roon throws up.
Both the Client and Core Roon software have Full Disk Access in System Prefs>Security.
It turns out that I was using the wrong “Export” menu. If you are inside a playlist, there are three different “Export” options, and they look very similar, but do different things. The KB article is not helpful, since it doesn’t tell you which to use. There is no indication in the Roon interface that one method works differently from another.