I use a macro to cast Fire Breath on my evoker, which includes: “/cast [nomod] Fire Breath”
This macro works when my spec includes the talent “Font of Magic” from the second to last row of the Devastation evoker tree.
If “Font of Magic” is not taken, the macro still shows the correct Fire Breath icon, but is greyed out. Pressing the macro results in “Spell not learned” and no cast.
The only workarounds seem to be taking the talent “Font of Magic” or not using a macro to cast Fire Breath.
UPDATE: There is a similar problem with the mage talent “Displacement”. It also does not work when macro’d, but will work when the ability is dragged from the spellbook directly to a hotkey. I have not identified a talent that Displacement is linked to to make it work with macros.