Comment 2 for bug 964270

I got a work around on this. The problem is to assign something with ALT. I think it confuses the system with HUD shortcut. I changed my music keyboard shortcuts from ALT+X/Z/C to something else like a keyboard assigned button BACK, PLAY, FORWARD and it works. Ubuntu does not forget the shortcut.

Thus, it is just a clash between the shortcut of Hud and your custom assignment of ALT to another program that makes Ubuntu forget your shortcut but prioritize the HUD one. In this sense, the problem is "fixed".