Kuva Lich not registering stabs but still ranks up

[PretselKnight]

During a public kuva lich defense mission, I did my 1st stab on a kuva lich but they revealed 1st and 2nd requiem mods.
On my 2nd stab of the kuva lich, it still revealed the 1st and 2nd requiem mods, then the hp bar disappears, but its icon is still present and its model stood still
In the same mission another lich spawned from another player and it went smoothly as expected.
I restarted Warframe in case i was bugged, then checked the parazon stab history. It didnt register the 3rd stab but they still ranked up again.