I'm pretty sure that in the Crucible Kills grimoire card the pop ups that showed the progress towards the total kills with each class it incorrectly said "Hunters killed" and "Titans killed" when it should have been "Kills with Hunter" or "Kills with Titan". And when you completed the card there was no in game pop up whatsoever. So it could be possible that the game is glitched by mixing those two things together?