When using XFCE, the mixer plugin has no way to switch any Pulse settings, e.g. profile. Specifically, I can't change the audio output on my laptop to go to HDMI when I connect it to a TV. At least, I wouldn't have a slightest idea of how to do that if I were an average user that just started using the system. Apparently, I can easily do that if I run pavucontrol (has to be installed separately in Fedora XFCE spin) The XFCE audio mixer should probably detect that Pulse is in use and at the very least suggest to the user which additional applications they may want to install and/or run to work with the sound.
Consider xfce4-pulseaudio-plugin instead.
Easy for you to say, but there's absolutely no integration! Average user may not even have it installed; but some things can only be configured through there. Furthermore, some actions done on Audio Mixer are irreversible. For example, when I lower the volume using the systray icon to 0, it stays locked on mute and can't be unlocked in Audio Mixer at all! There isn't even a slight hint that the device is muted elsewhere. Again, please consider some integration or at least a prominent warning message to the user
I'm not telling you that it's a good situation. I'm telling you that xfce4-mixer is going to get a final 4.12 release and then that it's unmaintained. This bug won't be fixed.
Oh I see, xfce4-pulseaudio-plugin wil supersede mixer?
Well, probably. That's more or less the plan right now, but time will tell. There are other (non-coded) ideas too, but xfce4-pulseaudio-plugin has the advantage of being already working code :-)