Shift Macro only Works when in combat

You’re missing [mod:shift,harm] as the first condition.

#showtooltip
/cast [mod:shift,harm] [mod:shift,@targettarget,harm] [mod:shift,@targettargettarget,harm] [mod:shift,@focus,harm] [mod:shift,@focustarget,harm] [mod:shift] Flame Shock; [harm] [@targettarget,harm] [@targettargettarget,harm] [@focus,harm] [@focustarget] [] Lava Burst

I personally would drop all instances of @TargetTargetTarget it’s a pretty niche use case.

Different approach if you’re interested.