I tried to rework speedboots.

I had a pair of 6-star rare boots with defense.

I had epic ore to use so i went to the artifact upgrade tab, rework.  I had epic ore in storage.

I selected the boots and hit the reword button.

Because they were rare and not epic the game asked me for confirmation, which i gave.

The boots got transformed... holy shit, SPEED main stat AND 7 % HP AND 6% CritRate.  Amazing !

I hit OK and... The boots disappeared and the old pair was there, mocking me.  My ore was gone and my boots were the same as before.  What the heck ?

What happened with my premium boots ? Why did they vanish ???