[GAMEPLAY][QUESTION] Warmogs passive disappears when Mordekaiser is damaged when his Passive is up?

Warmogs passive doesnt disappear when champ inflicts self damage and shields prevent recall animations from being interrupted. These also apply to morde and his passive. But Warmog passive seems to disappear when morde is taking damage with his shield up. Is this supposed to happen?

If it is supposed to happen: Warmogs icon does not go on countdown but passive disappears (only applies if shield is not broken through).

If it isnt supposed to happen: Bug? Mybe? better explaination or consistency of shielding?