I’ve reported this in the Volumio 1.5 for Raspberry PI Feedback Thread.
The problem is that the script creates an .pls in the style of a .m3u
the script behind it should be changed so that it either makes a proper .pls or make it an .m3u
You can edit it via the command lind (ssh) or samba using the windows share.
To add/delete webradios you can access the “WEBRADIOS” folder from your finder/windows explorer > network > volumio > login as a registered user > user : pi password : raspberry
Webradios, open total commander, There are disks: C, D and so on. Next to it is NET. Click Here, you find volumio there and upload pls or m3u. Without total commander you can do it using network place icon on your desktop. If you use Windows of course.