The artifact spell of balance is New Moon which cycle between NewMoon > HalfMoon > FullMoon > NewMoon >...
When you cast one you pass to the next one.
and the spell has 3 charges, but that's 3 considered different spells (202767, 202768, 202771), and everything charges/coodown/... is stored in New moon.
So, to determine the next spell to cast, I have a temp var that's called nextMoon where i store the next spell based on what i'm currently casting.
See here
AethysRotation - WoW Addon - Attempt to provide the useful and precise informations to execute the best possible DPS rotation in every situation.

The problem is :
When the player is casting Full Moon, the next spell is New Moon, so in nextMoon I have new moon.
BUT
newMoon is the ability tha you have in the codex and it switches it's icon by itself between the spells.
So, when I am casting fullMoon, nextmoon becomes newmoon
BUT
NewMoon still has the icon of FullMoon.

What i want is to tell the player taht when he is casting full moon, his next moon will be new moon but I can't do that...
I tried finding other spells with the same icon as new moon but that doesn't work
Everything works well for the rest because i can force cast HalfMoon and Fullmoon because that's different spells that stays with their icons

I don't think it's a cache problem. The thing is, Full moon hasn't finished casting, so it's normal for the New Moon icon to still show Full Moon. Is there a way to force a specific icon on a Spell ?

Did you try to maybe use CastAnnotate? It was added by Kojiyama iirc and allow to label an icon with text

I could but this would not solve the issue

Solved with ba82ef3

You'll have to force a texture clear :) That should update it.
The cache does cache each texture, although I'll probably remove this really soon since it's probably not a performance gain (need to double check).