Quote Originally Posted by Ihm View Post
It's because whatever job you're on doesn't have Inner quiet because in all SE's wisdom, they decided to make it so you can't use icons for stuff you don't have on that job.
The /macroicon command doesn't just change the icon to the desired art, it will actually behave the same way visually as if you had the button for that ability on your bars. I.E. the same states such as GCD, CD, "Combo Ready," grayed out etc, based on the current state of the ability selected in the macroicon line.

This would be pointless if you could set an ability you didn't have access to because abilities you can't use have no states to call upon. That being said, if you want to use the art for an ability on another job for a macro, you're free to do that, simply select the icon in the macro panel, and then don't use the /macroicon command in your macro.