Focus sash doesn't not work on ohko Moves

[Hart1dechu]

As u must know, a dead pokemon in battle, will be spoilt by having his profile becoming red before he dies.

Which is not the case for my eelektross, his profile still in the right color, after sheer cold release, which means, he survived with 1HP, as the item "Focus sash" is meant to do, but just after, he dies with no reason