Fully up2date rawhide system, try changing the audio volume of your system with the volume up / down keys on your keyboard. The dialog shown shows a bar indicating the volume setting and used to display (F-9 and earlier) a speaker icon above this, now it just shows a missing icon symbol.
Note: I tried changing my icon theme to see if that would fix it and it didn't fix it immediately but after a logout / login its fixed now. My new icon theme is Fedora, not sure what my old theme was.
I don't see how this would ever be an F10Blocker. Anyway, fixed